Extrusion die for metallic material

ABSTRACT

In some preferred embodiments, an extrusion die  10  for a metallic material includes a die case  20  having a pressure receiving portion  21  with a metallic material pressure receiving surface  22  faced rearward against an extrusion direction, a male die  30  disposed in the die case  20 , and a female die  40  disposed in the die case  20 . The pressure receiving portion  21  is formed into a convex configuration protruded rearward, and a porthole  24  for introducing the metallic material is provided in an outer periphery of the pressure receiving portion  21 . A ratio of a flat state opening area Sb of a porthole inlet portion  24   e  to a flat state area Sa of the pressure receiving portion  21  is set to 0.15 to 0.80. The extrusion die is configured such that the metallic material pressurized against the metallic material pressure receiving surface  22  is introduced into the die case  20  via the porthole  24  and passes through the extrusion hole  11.

This application claims priority to Japanese Patent Application No.2006-271726 filed on Oct. 3, 2006, Japanese Patent Application No.2006-275031 filed on Oct. 6, 2006, Japanese Patent Application No.2007-56953 filed on Mar. 7, 2007, Japanese Patent Application No.2007-57124 filed on Mar. 7, 2007, and U.S. Provisional Application Ser.No. 60/887,044 filed on Jan. 29, 2007, the entire disclosures of whichare incorporated herein by reference in their entireties.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is an application filed under 35 U.S.C.§111(a) claimingthe benefit pursuant to 35 U.S.C. §119(e)(1) of the filing date of Ser.No. 60/887,044 filed on Jan. 29, 2007, pursuant to 35 U.S.C.§111(b).

TECHNICAL FIELD

The present invention relates to an extrusion die for a metallicmaterial used for extruding a metallic material and its related art.

BACKGROUND ART

As an extrusion die used for manufacturing a metallic hollow extrudedproduct, such as, e.g., an aluminum heat exchanging tube for use in aheat exchanger for car air-conditioners, there are a porthole die asshown in FIG. 44A, a spider die as shown in FIG. 44B, and a bridge dieas shown in FIG. 44C.

In these extrusion dies, a male die 1 and a female die 2 are combined ina state in which the mandrel 1 a of the male die 1 is placed in thecorresponding die hole 2 a of the female die 2 to define a circularextrusion hole by and between the mandrel 1 a and the die hole 2 a. Theextrusion die is configured such that a metallic billet (metallicmaterial) pressed against the billet pressure receiving surface(metallic material pressure receiving surface 1 b) of the male die 1 isintroduced into the dies 1 and 2 via material introduction portions 1 cand then passed through the extrusion hole while being plasticallydeformed, so that an extruded member having a cross-sectional shapecorresponding to the cross-sectional shape of the extrusion hole isformed.

In such an extrusion die, since large stress due to the pressing of themetallic billet is applied to the billet pressure receiving surface 1 bof the male die 1, the stress may cause generation of cracks in theperiphery of the pressure receiving portion of the die, which maysometimes make it difficult to attain sufficiently long die life.

Under the circumstances, an extrusion die for a metallic material asdisclosed by the below-listed Patent Documents 1 and 2 has beenconventionally proposed. In the die, the billet pressure receivingsurface of the male die is formed into a convex shape protruded in adirection opposite to the billet extruding direction (i.e., protrudedrearward) so that the pressing force of the metallic billet to beapplied to the billet pressure receiving surface can be received by abridge portion of the male die.

Patent Document 1: Japanese Unexamined Laid-open Utility ModelPublication No. S53-102938 (see claims, FIGS. 3-5)

Patent Document 2: Japanese Examined Laid-open Patent Publication No.H06-81644 (see claims, drawings)

In the conventional extrusion die disclosed in the aforementioned PatentDocuments 1 and 2, since the billet pressure receiving surface is formedinto a convex configuration, the bridge portion is still insufficient instrength although the strength of the male die, such as the resistanceto pressure against a metallic billet, can be improved to some extent.Therefore, in order to secure sufficient strength of the bridge portion,the size of the male die such as the thickness of the bridge portion hasto be increased, which results in not only an increased size and anincreased weight but also an increased cost.

Especially in the case of extruding an extruded article having acomplicated configuration using an extrusion die, it is necessary tostably and smoothly introduce the metallic material into the extrusionhole from the material introducing portion of the male die. In theaforementioned conventional extrusion die, however, the metallicmaterial which flows from the material introducing portion of the maledie into the space between the male die and the female die is disturbedby the bridge portion of the male die. This prevents smooth introductionof the metallic material, causing deteriorated dimensional accuracy ofthe extruded article, which in turn makes it difficult to attain highquality.

The description herein of advantages and disadvantages of variousfeatures, embodiments, methods, and apparatus disclosed in otherpublications is in no way intended to limit the present invention.Indeed, certain features of the invention may be capable of overcomingcertain disadvantages, while still retaining some or all of thefeatures, embodiments, methods, and apparatus disclosed therein.

Other objects and advantages of the present invention will be apparentfrom the following preferred embodiments.

DISCLOSURE OF INVENTION

The preferred embodiments of the present invention have been developedin view of the above-mentioned and/or other problems in the related art.The preferred embodiments of the present invention can significantlyimprove upon existing methods and/or apparatuses.

The present invention was made to solve the aforementioned problems ofconventional techniques, and aims to provide an extrusion die for ametallic material capable of obtaining a high quality extruded articlewhile reducing the cost and size of the die and securing sufficientstrength and durability of the die.

The present invention also aims to provide related technologies capableof attaining the aforementioned objects, such as, e.g., a productionmethod of an extruded article, a production method of an extrudedtubular member, a production method of a multi-passage hollow member, adie case for an extrusion die, an extrusion method of a metallicmaterial, and an extruder for a metallic material.

The present invention provides the following means to attain theaforementioned objects.

[1] An extrusion die for a metallic material, comprising:

a die case having a pressure receiving portion with an outer surfacefunctioning as a metallic material pressure receiving surface, the diecase being disposed with the metallic material pressure receivingsurface faced rearward against an extrusion direction of the metallicmaterial;

a male die disposed in the die case; and

a female die disposed in the die case to define an extrusion holebetween the male die and the female die,

wherein the pressure receiving surface is formed into a convexconfiguration protruded rearward, and a porthole for introducing themetallic material is provided in an outer periphery of the pressurereceiving portion,

wherein a ratio of an opening area of an inlet portion of the portholedefined by a plan view as seen from an axial upstream side (a plan stateopening area of the inlet portion of the porthole) to an area of thepressure receiving portion defined by a plan view as seen from the axialupstream side (a plan state area of the pressure receiving portion) isset to 0.15 to 0.80, and

wherein the extrusion die is configured such that the metallic materialpressurized against the metallic material pressure receiving surface isintroduced in the die case via the porthole and passes through theextrusion hole.

[2] The extrusion die for a metallic material as recited in theaforementioned Item 1, wherein the metallic material pressure receivingportion is constituted by a convex spherical surface of a ⅙ to 4/6sphere.

[3] The extrusion die for a metallic material as recited in theaforementioned Item 1 or 2, wherein a plurality of portholes are formedat regular intervals in a circumferential direction about an axis of thedie case.

[4] The extrusion die for a metallic material as recited in any one ofthe aforementioned Items 1 to 3, wherein the porthole is arranged towardthe extrusion hole.

[5] The extrusion die for a metallic material as recited in any one ofthe aforementioned Items 1 to 4, wherein an inclination of an axis ofthe porthole with respect to an axis of the die case is set to 3 to 45°.

[6] The extrusion die for a metallic material as recited in any one ofthe aforementioned Items 1 to 5, wherein the extrusion hole is formedinto a flat cross-sectional configuration with a width larger than athickness, and

wherein the portholes are formed at positions corresponding to thicknessdirectional both sides of the extrusion die.

[7] The extrusion die for a metallic material as recited in any one ofthe aforementioned Items 1 to 6,

wherein the male die and the female die define a flat circular extrusionwith a height (thickness) smaller than a width,

wherein a portion of the male die corresponding to the extrusion hole isformed into a comb-like configuration having a plurality of passageforming protrusions arranged in a width direction, and

wherein the extrusion die is configured such that the metallic materialpasses through the extrusion hole to form a multi-passage hollow memberwith a plurality of passages arranged in a width direction.

[8] The extrusion die for a metallic material as recited in any one ofthe aforementioned Items 1 to 6, wherein the male die and the female diedefine a circular extrusion hole, and the extrusion die is configuredsuch that the metallic material passes through the extrusion hole toform a tubular member circular in cross-section.

[9] The extrusion die for a metallic material as recited in any one ofthe aforementioned Items 1 to 8, wherein the metallic material is analuminum or its alloy.

[10] A production method of an extruded article, comprising the step offorming an extruded article using the extrusion die as recited in anyone of the aforementioned Items 1 to 9.

[11] A production method of a multi-passage hollow member, comprisingthe step of forming an multi-passage extruded article using theextrusion die as recited in the aforementioned Item 7.

[12] A production method of an extruded tubular member, comprising thestep of forming the extruded article using the extrusion die as recitedin the aforementioned Item 8.

[13] A die case for an extrusion die, comprising a pressure receivingportion with an outer surface functioning as a metallic materialpressure receiving surface faced rearward against an extrusion directionof the metallic material, the die case being configured to mount a maledie and a female die therein,

wherein the pressure receiving surface is formed into a convexconfiguration protruded rearward, and a porthole for introducing themetallic material is provided in an outer periphery of the pressurereceiving portion,

wherein a ratio of an opening area of an inlet portion of the portholedefined by a plan view as seen from an axial upstream side (a plan stateopening area of the inlet portion of the porthole) to an area of thepressure receiving portion defined by a plan view as seen from the axialupstream side (a plan state area of the pressure receiving portion) isset to 0.15 to 0.80, and

wherein the die case is configured such that the metallic materialpressurized against the metallic material pressure receiving surface isintroduced into the die case via the porthole and passes through theextrusion hole.

[14] The die case for an extrusion die as recited in the aforementionedItem 13, wherein the metallic material pressure receiving portion isconstituted by a convex spherical surface of a ⅙ to 4/6 sphere.

[15] An extrusion method for a metallic material, comprising the stepsof:

preparing a die case, wherein the die case comprises a pressurereceiving portion with an outer surface functioning as a metallicmaterial pressure receiving surface faced rearward against an extrusiondirection of the metallic material, a male die mounted in the die case,and a female die mounted in the die case for defining an extrusion holebetween the male die and the female die, wherein the pressure receivingsurface is formed into a convex configuration protruded rearward, and aporthole for introducing the metallic material is provided in an outerperiphery of the pressure receiving portion, and wherein a ratio of anopening area of an inlet portion of the porthole defined by a plan viewas seen from an axial upstream side (a plan state opening area of theinlet portion of the porthole) to an area of the pressure receivingportion defined by a plan view as seen from the axial upstream side (aplan state area of the pressure receiving portion) is set to 0.15 to0.80; and

introducing the metallic material pressurized against the metallicmaterial pressure receiving surface into the die case via the portholeto pass through the extrusion hole.

[16] An extruder for a metallic material equipped with a container andan extrusion die set in the container and configured to supply themetallic material in the container to the extrusion die,

wherein the extrusion die comprises:

a die case having a pressure receiving portion with an outer surfacefunctioning as a metallic material pressure receiving surface, the diecase being disposed with the metallic material pressure receivingsurface faced rearward against an extrusion direction of the metallicmaterial;

a male die disposed in the die case; and

a female die disposed in the die case to define an extrusion holebetween the male die and the female die,

wherein the pressure receiving surface is formed into a convexconfiguration protruded rearward, and a porthole for introducing themetallic material is provided in an outer periphery of the pressurereceiving portion,

wherein a ratio of an opening area of an inlet portion of the portholedefined by a plan view as seen from an axial upstream side (a plan stateopening area of the inlet portion of the porthole) to an area of thepressure receiving portion defined by a plan view as seen from the axialupstream side (a plan state area of the pressure receiving portion) isset to 0.15 to 0.80, and

wherein the extrusion die is configured such that the metallic materialpressurized against the metallic material pressure receiving surface isintroduced into the die case via the porthole and passes through theextrusion hole.

[17] An extrusion die for a metallic material, comprising:

a die case having a pressure receiving portion with an outer surfacefunctioning as a metallic material pressure receiving surface, the diecase being disposed with the metallic material pressure receivingsurface faced rearward against an extrusion direction of the metallicmaterial;

a male die disposed in the die case; and

a female die disposed in the die case to define an extrusion holebetween the male die and the female die,

wherein the pressure receiving surface is formed into a convexconfiguration protruded rearward, a porthole for introducing themetallic material is provided in an outer periphery of the pressurereceiving portion, and an opening area of the inlet portion of theporthole is set to be larger than a passage cross-sectional area of aninside of the porthole, and

wherein the extrusion die is configured such that the metallic materialpressurized against the metallic material pressure receiving surface isintroduced into the die case via the porthole and passes through theextrusion hole.

[18] The extrusion die for a metallic material as recited in theaforementioned Item 17, wherein the porthole is configured such that apassage cross-sectional area gradually decreases from the inlet portiontoward an inside of the porthole.

[19] The extrusion die for a metallic material as recited in theaforementioned Item 17 or 18, wherein the porthole is configured suchthat a radial length (thickness) of the inlet portion is set to belarger than a thickness of an inside of the porthole.

[20] The extrusion die for a metallic material as recited in any one ofthe aforementioned Items 17 to 19, wherein the porthole is configuredsuch that a circumferential length (width) of the inlet portion of theporthole is set to be larger than a width of an inside of the porthole.

[21] The extrusion die for a metallic material as recited in any one ofthe aforementioned Items 17 to 20, wherein a chambered portion is formedat an outer side portion of a peripheral edge of the inlet portion ofthe porthole.

[22] The extrusion die for a metallic material as recited in any one ofthe aforementioned Items 17 to 21, wherein a chambered portion is formedat an inner side portion of a peripheral edge of the inlet portion ofthe porthole.

[23] The extrusion die for a metallic material as recited in any one ofthe aforementioned Items 17 to 22, wherein an inclination angle of anouter side surface of an inner peripheral surface of the porthole to anaxis of the extrusion die is set to be larger than an inclination angleof an inner side surface of an inner peripheral surface of the portholeto the axis of the extrusion die.

[24] The extrusion die for a metallic material as recited in any one ofthe aforementioned Items 17 to 23, wherein the metallic materialpressure receiving portion is constituted by a convex spherical surfaceof a ⅙ to 4/6 sphere.

[25] The extrusion die for a metallic material as recited in any one ofthe aforementioned Items 17 to 24, wherein a plurality of portholes areformed at regular intervals in a circumferential direction about an axisof the die case.

[26] The extrusion die for a metallic material as recited in any one ofthe aforementioned Items 17 to 25, wherein the extrusion hole is formedinto a flat cross-sectional configuration with a width larger than athickness, and

wherein the portholes are formed at positions corresponding to thicknessdirectional both sides of the extrusion die.

[27] The extrusion die for a metallic material as recited in any one ofthe aforementioned Items 17 to 26,

wherein the male die and the female die define a flat circular extrusionhole with a height (thickness) smaller than a width,

wherein a portion of the male die corresponding to the extrusion hole isformed into a comb-like configuration having a plurality of passageforming protrusions arranged in a width direction, and

wherein the extrusion die is configured such that the metallic materialpasses through the extrusion hole to form a multi-passage hollow memberwith a plurality of passages arranged in a width direction.

[28] The extrusion die for a metallic material as recited in any one ofthe aforementioned Items 17 to 26, wherein the male die and the femaledie define a circular extrusion hole, and wherein the extrusion die isconfigured such that the metallic material passes through the extrusionhole to form a tubular member circular in cross-section.

[29] The extrusion die for a metallic material as recited in any one ofthe aforementioned Items 17 to 28, wherein the metallic material is analuminum or its alloy.

[30] The production method of an extruded article, comprising the stepof forming the extruded article using the extrusion die as recited inany one of the aforementioned Items 17 to 28.

[31] The production method of a multi-passage hollow member, comprisingthe step of forming the multi-passage hollow member using the extrusiondie as recited in the aforementioned Item 27.

[32] A production method of an extruded tubular member, comprising thestep of forming the extruded tubular member using the extrusion die asrecited in the aforementioned Item 28.

[33] A die case for an extrusion die, comprising a pressure receivingportion with an outer surface functioning as a metallic materialpressure receiving surface faced rearward against an extrusion directionof the metallic material, the die case being configured to mount a maledie and a female die therein,

wherein the pressure receiving surface is formed into a convexconfiguration protruded rearward, a porthole for introducing themetallic material is provided in an outer periphery of the pressurereceiving portion, and an opening area of the inlet portion of theporthole is set to be larger than a passage cross-sectional area of aninside of the porthole, and

wherein the die case is configured such that the metallic materialpressurized against the metallic material pressure receiving surface isintroduced into the die case via the porthole and passes through theextrusion hole.

[34] The die case for an extrusion die as recited in the aforementionedItem 33, wherein the metallic material pressure receiving portion isconstituted by a convex spherical surface of a ⅙ to 4/6 sphere.

[35] An extrusion method for a metallic material, comprising the stepsof:

preparing a die case, wherein the die case comprises a pressurereceiving portion with an outer surface functioning as a metallicmaterial pressure receiving surface faced rearward against an extrusiondirection of the metallic material, a male die mounted in the die case,and a female die mounted in the die case for defining an extrusion holebetween the male die and the female die, wherein the pressure receivingsurface is formed into a convex configuration protruded rearward, and aporthole for introducing the metallic material is provided in an outerperiphery of the pressure receiving portion, and wherein an opening areaof the inlet portion of the porthole is set to be larger than a passagecross-sectional area of an inside of the porthole; and

introducing the metallic material pressurized against the metallicmaterial pressure receiving surface into the die case via the portholeto pass through the extrusion hole.

[36] An extruder for a metallic material equipped with a container andan extrusion die set in the container and configured to supply themetallic material in the container to the extrusion die,

wherein the extrusion die comprises:

a die case having a pressure receiving portion with an outer surfacefunctioning as a metallic material pressure receiving surface, the diecase being disposed with the metallic material pressure receivingsurface faced rearward against an extrusion direction of the metallicmaterial;

a male die disposed in the die case; and

a female die disposed in the die case to define an extrusion holebetween the male die and the female die,

wherein the pressure receiving surface is formed into a convexconfiguration protruded rearward, and a porthole for introducing themetallic material is provided in an outer periphery of the pressurereceiving portion,

wherein an opening area of the inlet portion of the porthole is set tobe larger than a passage cross-sectional area of an inside of theporthole, and

wherein the extrusion die is configured such that the metallic materialpressurized against the metallic material pressure receiving surface isintroduced into the die case via the porthole D and passes through theextrusion hole.

EFFECTS OF THE INVENTION

According to the extrusion die for a metallic material as recited in theaforementioned Item [1], since the pressure receiving surface is formedinto a convex surface configuration, when the metallic material ispressed against the pressure receiving surface, the pressing force ofthe metallic material can be received by the pressure receiving surfacein a dispersed manner, which can decrease the pressing force in thenormal direction at each portion of the pressure receiving surface. As aresult, the strength against the pressing force of the metallic materialcan be increased, which makes it possible to attain sufficientdurability. That is, when the metallic material is pressed against thepressure receiving surface formed into a convex surface configuration,the compressing force toward the axis of the pressure receiving portionwill be applied to each portion of the pressure receiving surface, whichreduces the shearing force to be generated at the die case at the timeof the extrusion processing. As a result, at the portion exposed to thehollow portion of the die case where the largest shearing force will begenerated, the shearing force to be generated at the portion can bereduced, which in turn can increase the strength of the die against thepressing force of the metallic material.

Furthermore, in the present invention, the porthole for introducing amaterial is formed in the pressure receiving portion of the die casecovering the male die and the female die. In other words, the front end(downstream side) wall portion of the pressure receiving portion isintegrally formed in a circumferentially continued manner. The existenceof this continuous peripheral wall can further increase the strength ofthe die case, which in turn can further increase the strength of theentire extrusion die. Thus, in the extrusion die of this invention,there is no portion weak in strength, such as a conventional bridgeportion, and therefore it is not required to increase the size, such as,e.g., the thickness, beyond the necessity for the purpose of increasingthe strength, which makes it possible to attain the size and weightreduction as well as the cost reduction.

Furthermore, in the invention as recited in the aforementioned Item [1],since the ratio of the plan state opening area of the porthole inletportion to the plan state area of the pressure receiving portion is setto the specific value, the metallic material can be smoothly introducedinto the inside of the die from the porthole inlet portion, resulting indecreased extrusion pressure (extrusion load) of the metallic materialagainst the pressure receiving surface. Therefore, extrusion processingcan be performed smoothly and efficiently and longer die life can beattained.

According to the extrusion die for a metallic material as recited in theaforementioned Item [2], the extrusion pressure of the metallic materialto the pressure receiving surface can be more assuredly dispersed in abalanced manner, which in turn can make it possible to more assuredlyincrease the strength against the pressing force of the metallicmaterial. In detail, when the metallic material is pressed against thepressure receiving surface constituted by a specific convex sphericalsurface, compressing force in the direction toward the center of thepressure receiving portion will be more assuredly applied to eachportion of the pressure receiving surface, which more assuredly reducesthe shearing force to be generated in the die case at the time ofextrusion processing. As a result, at the portion exposed to the hollowportion of the die case where the largest shearing force will begenerated, the shearing force to be generated at the portion can bereduced, which in turn can increase the strength of the die against thepressing force of the metallic material.

According to the extrusion die for a metallic material as recited in theaforementioned Item [3], the metallic material can be evenly introducedtoward the extrusion hole from the circumferential direction of the die,enabling stable extrusion.

According to the extrusion die for a metallic material as recited in theaforementioned Items [4] and [5], the metallic material can be evenlyintroduced toward the extrusion hole from the porthole.

According to the extrusion die for a metallic material as recited in theaforementioned Item [6], a flat extruded product can be formed with ahigh degree of dimensional accuracy.

According to the extrusion die for a metallic material as recited in theaforementioned Item [7], a multi-passage hollow member with a pluralityof passages arranged in the width direction can be formed assuredly.

According to the extrusion die for a metallic material as recited in theaforementioned Item [8], a tubular member circular in cross-section canbe formed assuredly.

According to the extrusion die for a metallic material as recited in theaforementioned Item [9], an aluminum or aluminum alloy extruded articlecan be produced.

According to the invention as recited in the aforementioned Item [10], aproduction method for an extruded article having the same effects asmentioned above can be provided.

According to the invention as recited in the aforementioned Item [11], aproduction method for a multi-passage hollow member having the sameeffects as mentioned above can be provided.

According to the invention as recited in the aforementioned Item [12], aproduction method for an extruded tubular member having the same effectsas mentioned above can be provided.

According to the invention as recited in the aforementioned Item [13], adie case for an extrusion die having the same effects as mentioned abovecan be provided.

According to the invention as recited in the aforementioned Item [14],by the same reasons as mentioned in the aforementioned Item [2], theextrusion pressure of the metallic material to the pressure receivingsurface can be more assuredly dispersed in a balanced manner, which inturn can make it possible to more assuredly increase the strengthagainst the extrusion force of the metallic material.

According to the invention as recited in the aforementioned Item [15],an extrusion method for a metallic material having the same effects asmentioned above can be provided.

According to the invention as recited in the aforementioned Item [16],an extruder for a metallic material having the same effects as mentionedabove can be provided.

According to the extrusion die for a metallic material as recited in theaforementioned Item [17], since the pressure receiving surface is formedinto a convex surface configuration, when the metallic material ispressed against the pressure receiving surface, the pressing force ofthe metallic material can be received by the pressure receiving surfacein a dispersed manner, resulting in reduced extrusion force in thenormal direction at each portion of the pressure receiving surface. As aresult, the strength against the pressing force of the metallic materialcan be increased, resulting in sufficient durability. In detail, whenthe metallic material is pressed against the pressure receiving surfaceconstituted by a specific convex spherical surface, compressing force inthe direction toward the center of the pressure receiving portion willbe more assuredly applied to each portion of the pressure receivingsurface, which more assuredly reduces the shearing force to be generatedin the die case at the time of extrusion processing. As a result, at theportion exposed to the hollow portion of the die case where the mostlarge shearing force will be generated, the shearing force to begenerated at the portion can be reduced, which in turn can increase thestrength of the die against the pressing force of the metallic material.

Furthermore, in the invention as recited in the aforementioned Item[17], the porthole for introducing a material is formed in the pressurereceiving portion of the die case covering the male die and the femaledie. In other words, the front end (downstream side) wall portion of thepressure receiving portion is integrally formed in a circumferentiallycontinued manner. The existence of this continuous peripheral wall canfurther increase the strength of the die case, which in turn can furtherincrease the strength of the entire extrusion die. Thus, in the die ofthis invention, there is no portion weak in strength, such as aconventional bridge portion, and therefore it is not required toincrease the size, such as, e.g., the thickness, beyond the necessityfor the purpose of increasing the strength, which makes it possible toattain the size and weight reduction as well as the cost reduction.

Furthermore, in the invention as recited in the aforementioned Item[17], since the opening area of the inlet portion of the porthole isformed to be larger than the passage cross-sectional area of the insideof the porthole, the metallic material can be smoothly introduced fromthe inlet portion, resulting in reduced pressing force (extrusion load)to the pressure receiving surface of the metallic material. This in turnenables efficient and smooth extrusion processing.

Furthermore, since the passage cross-sectional area of the inside of theporthole is small, the void gap rate of the die case by the portholesbecomes small, which can further increase the strength of the die case,which in turn can further increase the strength of the entire die.

According to the extrusion die for a metallic material as recited in theaforementioned Item [18], since the porthole is configured such that apassage cross-sectional area gradually decreases from the inlet portiontoward an inside of the porthole, no sudden change in flow resistance ofthe metallic material passing through the porthole occurs, which makesit possible to more smoothly pass the metallic material through theporthole.

According to the extrusion die for a metallic material as recited in theaforementioned Items [19] to [23], the aforementioned effects can beobtained more assuredly.

According to the extrusion die for a metallic material as recited in theaforementioned Item [24], the extrusion pressure of the metallicmaterial to the pressure receiving surface can be more assuredlydispersed in a balanced manner, which in turn can make it possible tomore assuredly increase the strength against the extrusion force of themetallic material. In detail, when the metallic material is pressedagainst the pressure receiving surface constituted by a specific convexspherical surface, compressing force in the direction toward the centerof the pressure receiving portion will be more assuredly applied to eachportion of the pressure receiving surface, which more assuredly reducesthe shearing force to be generated in the die case at the time ofextrusion processing. As a result, at the portion exposed to the hollowportion of the die case where the largest shearing force will begenerated, the shearing force to be generated at the portion can bereduced, which in turn can increase the strength of the die against thepressing force of the metallic material.

According to the extrusion die for a metallic material as recited in theaforementioned Item [25], the metallic material can be evenly introducedtoward the extrusion hole from the circumferential direction of the die,enabling stable extrusion.

According to the extrusion die for a metallic material as recited in theaforementioned Item [26], a flat extruded product can be formed with ahigh degree of dimensional accuracy.

According to the extrusion die for a metallic material as recited in theaforementioned Item [27], a multi-passage hollow member with a pluralityof passages arranged in the width direction can be formed assuredly.

According to the extrusion die for a metallic material as recited in theaforementioned Item [28], a tubular member circular in cross-section canbe formed assuredly.

According to the extrusion die for a metallic material as recited in theaforementioned Item [29], an aluminum or aluminum alloy extruded articlecan be produced.

According to the invention as recited in the aforementioned Item [30], aproduction method for an extruded article having the same effects asmentioned above can be provided.

According to the invention as recited in the aforementioned Item [31], aproduction method for a multi-passage hollow member having the sameeffects as mentioned above can be provided.

According to the invention as recited in the aforementioned Item [32], aproduction method for an extruded tubular member having the same effectsas mentioned above can be provided.

According to the invention as recited in the aforementioned Item [33], adie case for an extrusion die having the same effects as mentioned abovecan be provided.

According to the invention as recited in the aforementioned Item [34],by the same reasons as mentioned in the aforementioned Item [24], theextrusion pressure of the metallic material to the pressure receivingsurface can be more assuredly dispersed in a balanced manner, which inturn can make it possible to more assuredly increase the strengthagainst the extrusion force of the metallic material.

According to the invention as recited in the aforementioned Item [35],an extrusion method for a metallic material having the same effects asmentioned above can be provided.

According to the invention as recited in the aforementioned Item [36],an extruder for a metallic material having the same effects as mentionedabove can be provided.

The above and/or other aspects, features and/or advantages of variousembodiments will be further appreciated in view of the followingdescription in conjunction with the accompanying figures. Variousembodiments can include and/or exclude different aspects, featuresand/or advantages where applicable. In addition, various embodiments cancombine one or more aspect or feature of other embodiments whereapplicable. The descriptions of aspects, features and/or advantages ofparticular embodiments should not be construed as limiting otherembodiments or the claims.

BRIEF DESCRIPTION OF DRAWINGS

The preferred embodiments of the present invention are shown by way ofexample, and not limitation, in the accompanying figures, in which:

FIG. 1 is a perspective view showing an extrusion die according to afirst embodiment of the present invention;

FIG. 2 is an exploded perspective view showing the extrusion dieaccording to the first embodiment;

FIG. 3 is a rear view (top view) showing the extrusion die according tothe first embodiment;

FIG. 4 is a cutout perspective view showing the extrusion die accordingto the first embodiment;

FIG. 5 is a cross-sectional view showing the extrusion die according tothe first embodiment;

FIG. 6 is another cross-sectional view showing the extrusion dieaccording to the first embodiment;

FIG. 7 is an enlarged cutout perspective view showing the inside of theextrusion die according to the first embodiment;

FIG. 8 is an explanatory plan view of a plan state area of the pressurereceiving portion and a plan state opening area of the porthole inletportion of the extrusion die according to the first embodiment;

FIG. 9 is a perspective cutout principal portion of an extruder to whichthe extrusion die of the first embodiment is applied;

FIG. 10 is a cross-sectional view showing the extrusion die of the firstembodiment and the vicinity thereof in an extruder;

FIG. 11 is another cross-sectional view showing the extrusion die of thefirst embodiment and the vicinity thereof in the extruder;

FIG. 12 is a perspective view showing a multi-passage hollow memberextruded with an extruder according to the first embodiment;

FIG. 13 is an enlarged front cross-sectional view showing themulti-passage hollow member extruded with the extruder of the firstembodiment;

FIG. 14 is a cross-sectional view showing an extrusion die according toa first modification of this invention;

FIG. 15 is a perspective cutout view showing an extrusion die accordingto a second modification of this invention;

FIG. 16 is a cross-sectional view showing the extrusion die according tothe second modification of this invention;

FIG. 17 is a cross-sectional view showing an extrusion die according toa third modification of this invention;

FIG. 18 is a cross-sectional view showing an extrusion die according toa fourth modification of this invention;

FIG. 19 is a perspective view showing an extrusion die according to asecond embodiment of this invention;

FIG. 20 is an exploded perspective view showing the extrusion dieaccording to the second embodiment;

FIG. 21 is a cutout perspective view showing the extrusion die accordingto the second embodiment;

FIG. 22 is a cross-sectional view showing the extrusion die according tothe second embodiment;

FIG. 23 is another cross-sectional view showing the extrusion dieaccording to the second embodiment;

FIG. 24 is an enlarged cutout perspective view showing an inside of theextrusion die according to the second embodiment;

FIG. 25 is a cutout perspective view showing a principle portion of anextruder to which the extrusion die according to the second embodimentis applied;

FIG. 26 is a cross-sectional view showing a die according to the secondembodiment and the vicinity thereof mounted in an extruder;

FIG. 27 is another cross-sectional view showing a die according to thesecond embodiment and the vicinity thereof mounted in an extruder;

FIG. 28 is a perspective view showing a multi-passage hollow memberextruded with the extruder of the second embodiment;

FIG. 29 is an enlarged front view of the multi-passage hollow memberextruded with the extruder of the second embodiment;

FIG. 30 is a perspective view showing an extrusion die according to athird embodiment of this invention;

FIG. 31 is an exploded perspective view showing the extrusion dieaccording to the third embodiment;

FIG. 32 is a cutout perspective view showing the extrusion die accordingto the third embodiment;

FIG. 33 is a cross-sectional view showing the extrusion die according tothe third embodiment;

FIG. 34 is a perspective view showing an extrusion die according to afourth embodiment of this invention;

FIG. 35 is an exploded perspective view showing the extrusion dieaccording to the fourth embodiment;

FIG. 36 is a cutout perspective view showing the extrusion die accordingto the fourth embodiment;

FIG. 37 is a cross-sectional view showing the extrusion die according tothe fourth embodiment;

FIG. 38 is a cross-sectional view showing a die case of the extrusiondie according to the fourth embodiment;

FIG. 39 is a perspective view showing an extrusion die according to afifth embodiment of this invention;

FIG. 40 is an exploded perspective view showing the extrusion dieaccording to the fifth embodiment;

FIG. 41 is a cutout perspective view showing the extrusion die accordingto the fifth embodiment;

FIG. 42 is a cross-sectional view showing the extrusion die according tothe fifth embodiment;

FIG. 43 is a cross-sectional view showing a die case of the extrusiondie according to the fifth embodiment;

FIG. 44A is a perspective exploded view showing a porthole die as aconventional extrusion die;

FIG. 44B is a perspective exploded view showing a spider die as aconventional extrusion die; and

FIG. 44C is a perspective view showing a bridge die as a conventionalextrusion die.

BEST MODE FOR CARRYING OUT THE INVENTION

In the following paragraphs, some preferred embodiments of the inventionwill be described by way of example and not limitation. It should beunderstood based on this disclosure that various other modifications canbe made by those in the art based on these illustrated embodiments.

First Embodiment

FIGS. 1 to 13 are explanatory views showing an extrusion die for ametallic material according to a first embodiment of the presentinvention.

This extrusion die 10 for a metallic material according to the firstembodiment is designed to extrude a multi-passage hollow member (flatmulti-passage tube) 60 as shown in FIGS. 12 and 13.

The hollow member 60 is a metal member. In this embodiment, this hollowmember 60 constitutes a heat exchanging tube made of aluminum oraluminum alloy.

This hollow member 60 is a flat member having a width larger than thethickness for use in heat exchangers, such as, e.g., condensers for carair-conditioners. The hollow portion 61 of this hollow member 60 extendsin the tube length direction and is divided into a plurality of heatexchanging passages 63 by a plurality of partitions 62 arranged inparallel with each other. These passages 63 extend in the tube lengthdirection and are arranged in parallel with each other.

In the following explanation of this embodiment, a direction with whicha tube length direction perpendicularly intersects and along which thepassages 63 are arranged will be referred to as a “width direction” or a“lateral direction,” and a direction with which a tube length directionperpendicularly intersects and with which the width directionperpendicularly intersects will be referred to as a “height direction(thickness direction)” or a “vertical direction.” Furthermore, in thefollowing explanation of this embodiment, the “upstream side” withrespect to the extrusion direction will be referred to as a “rear side”,and the “downstream side” thereof will be referred to as a “front side.”

FIGS. 1 to 7 show an extrusion die 10 of this first embodiment. As shownin these figures, the extrusion die 10 of this embodiment is equippedwith a die case 20, a male die 30, a female die 40, and a flow controlplate 50.

The die case 20 has a hollow structure having a dome-shaped pressurereceiving portion 21 provided at the upstream side (rear side) withrespect to the extrusion direction of a metallic billet as a metallicmaterial and a base portion 25 provided at the downstream side (frontside).

The surface (rear surface) of the pressure receiving portion 21 opposedagainst the extrusion direction of a metallic billet is formed into abillet pressure receiving surface 22 functioning as a metallic materialpressure receiving surface. This billet pressure receiving surface 22 isformed into a convex surface configuration protruded in a directionopposite to the extrusion direction (i.e., in the rear direction).Concretely, this pressure receiving surface 22 is formed into ahemispherical convex configuration. Thus, the pressure receiving surface22 is formed so as to protrude rearward.

In the peripheral wall center of the pressure receiving portion 21, amale die holding slit 23 communicated with an internal hollow portion(welding chamber 12) is formed along the axis A1 of the die case 20.This male die holding slit 23 is formed into a flat rectangularcross-sectional configuration corresponding to the cross-sectionalconfiguration of the male die 30. Furthermore, as shown in FIG. 6, atboth side portions of the rear end side of the male die holding slit 23,engaging stepped portions 23 a and 23 a for engaging the male die 30,which will be mentioned later, are formed.

In the peripheral wall of the pressure receiving portion 21, a pair ofportholes 24 and 24 are formed at both sides of the axis A1. The inletportion 24 e of each porthole 24 is formed into an approximatelytrapezoidal configuration as seen from the upstream side of the axialdirection.

The pair of portholes 24 and 24 are arranged so that the outlet portions(front end portions) thereof face toward the below-mentioned extrusionhole 11.

As shown in FIG. 5, each porthole 24 is disposed such that the axis A2thereof approaches the axis A1 of the pressure receiving portion 21 asit advances toward the downstream side and intersects with the axis A1of the pressure receiving portion 21 in an inclined state. The detailstructure of, e.g., the inclination angle θ of the axis A2 of theporthole 24 and the area of the porthole 24 will be detailed later.

In this embodiment, it is constituted that the axis A1 of the die case20 and the axis of the pressure receiving portion 21 coincide with eachother.

The base portion 25 is integrally formed to the pressure receivingportion 21, and formed into an annular shape centered on the axis A1.The base portion 25 has a diameter larger than the diameter of thepressure receiving portion 21.

In this invention, the base portion 25 and the pressure receivingportion 21 are not required to be integrally formed, and can be formedseparately. Whether both the members 21 and 25 should be integrallyformed or separately formed can be arbitrarily selected in considerationof the maintenance performance, etc.

In the base portion 25, a cylindrical female die holding hole 26communicated with a welding chamber 12 and corresponding to thecross-sectional shape of the female die 40 is formed. The axis of thisfemale die holding hole 26 is constituted so as to align with the axisA1 of the die case 20.

At the rear end side of the inner peripheral surface of the female dieholding hole 26, as shown in FIGS. 4 to 6 for example, an engagingstepped portion 26 a for engaging a female die 40, which will beexplained later, via a flow control plate 50 is formed.

The front principle portion of the male die 30 is constituted as amandrel 31. As shown in FIGS. 6 and 7, the front end portion of themandrel 31 is configured to form the hollow portion 61 of the hollowmember 60 and has a plurality of passage forming protruded portions 33each corresponding to each passage 63 of the hollow member 60. Theseplural passage forming protruded portions 33 are arranged in the widthdirection of the mandrel 31 at certain intervals. The gap formed betweenthe adjacent passage forming protruded portions 33 and 33 is constitutedas a partition forming groove 32 for forming the partition 62 of thehollow member 60.

As shown in FIG. 2, at both the width direction side ends of the rearend portion of the male die 30, engaging protruded portions 33 a and 33a corresponding to the engaging stepped portions 23 a and 23 a of themale die holding slit 23 of the die case 20 are integrally formed so asto protrude sideways.

The male die 30 is inserted into the male die holding slit 23 of the diecase 20 from the side of the billet pressure receiving surface 22 andfixed therein. In this inserted state, the male die 30 is positionedwith the engaging protruded portions 33 a and 33 a of the male die 30engaged with the engaging stepped portions 23 a and 23 a. Thus, themandrel 31 of the male die 30 is held in the mandrel holding slit 23with the mandrel 31 forwardly protruded from the mandrel holding slit 23by a certain length.

The basal end surface (rear end surface) of the male die 30 is formedinto a partial hemispherical convex surface corresponding to the billetpressure receiving surface 22 of the die case 20. The basal end surface(rear end surface) of the male die 30 and the billet pressure receivingsurface 22 cooperatively form a prescribed smooth hemispherical convexsurface.

The female die 40 is formed into a cylindrical shape and provided withkey protrusions 47 and 47 arranged in parallel with the axis A1 at bothsides on the external peripheral surface thereof.

The female die 40 is provided with a die hole (bearing hole 41)corresponding to the mandrel 31 of the male die 30 and opened at therear end surface side and a relief hole 42 communicated with the diehole 41 and opened at the front end surface side.

The die hole 41 is provided with an inwardly protruded portion along theinner peripheral edge portion so that the outer peripheral portion ofthe hollow member 60 can be defined. The relief hole 42 is formed into atapered shape gradually increasing the thickness (height)) toward thefront end side (downstream side) and opened at the downstream side.

The flow control plate 50 is formed into around shape in externalperiphery corresponding to the cross-sectional shape of the female dieholding hole 26 of the die case 20. Corresponding to the die hole 41 ofthe female die 40, a central through-hole 51 is formed in the center ofthe flow control plate 50.

The flow control plate 50 has, at its both sides of the externalperipheral edge portion, key protrusions 57 and 57 corresponding to thekey protrusions 47 and 47 of the female die 40 are formed.

As shown in FIGS. 3 to 6, the female die 40 is accommodated and fixed inthe female die holding hole 26 of the die case 20 via the flow controlplate 50. With this state, the external peripheral surface of one endsurface (rear end surface) of the female die 40 is engaged with theengaging stepped portion 26 a of the female die holding hole 26 via theexternal peripheral edge portion of the flow control plate 50, so thatthe female die 40 and the flow control plate 50 are positioned in theaxial direction. Furthermore, the key protrusions 47 and 47 of thefemale die 40 and the key protrusions 57 and 57 of the flow controlplate 50 are engaged with the keyways (not illustrated) formed on theinner peripheral surface of the female die holding hole 26, so that thefemale die 40 and the flow control plate 50 are positioned in thecircumferential direction about the axis.

With this, the mandrel 31 of the male die 30 and the die hole 41 of thefemale die 40 are disposed corresponding to the central through-hole 51of the flow control plate 50. In this state, the mandrel 31 of the maledie 30 is disposed within the die hole 41 of the female die 40 to form aflat circular extrusion hole 11 between the mandrel 31 and the die hole41. Furthermore, a plurality of partition forming grooves 32 of themandrel 31 are arranged in parallel in the width direction in theextrusion hole 11, whereby a cross-sectional shape corresponding to thecross-sectional shape of the hollow member 60 is formed.

In this embodiment, as shown in FIG. 5, each of the portholes 24 and 24is formed such that the axis A2 of the porthole 24 inclines with respectto the axis A1 of the die case 20. In this embodiment, it is preferablethat the inclination angle θ of the axis A2 of the porthole 24 withrespect to the axis A1 of the die case 20 is set to 3 to 45°, morepreferably 10 to 35°, still more preferably 15 to 30°. When theinclination angle θ is set so as to fall within the above specifiedrange, the metallic material flows through the portholes 24 and 24 andthe welding chamber 12 in a stable manner, and then smoothly passesthrough around the entire periphery of the extrusion hole 11 in abalanced manner. As a result, a high quality extrusion molded article(extruded article) excellent in dimensional accuracy can be formed. Inother words, if the inclination angle θ is too small, the metallicmaterial passed through the portholes 24 and 24 and the welding chamber12 cannot be smoothly introduced into the extrusion hole 11, which maysometimes make it difficult to stably obtain a high quality extrusionmolded article. To the contrary, if the inclination angle θ is toolarge, the material flowing direction of the porthole 24 inclineslargely, which increases the metallic material extrusion resistance, andtherefore it is not preferable.

In this embodiment, as shown in FIG. 8, when the area of the pressurereceiving portion 21 defined by the plan view as seen from the upstreamside of the axial direction is defined as “a plan state area Sa of thepressure receiving portion 21,” and the opening area of the portholeinlet portion 24 e defined by the plan view as seen from the upstreamside of the axial direction is defined as “a plan state opening area Sbof the porthole inlet portion 24 e,” the plan state area Sa of thepressure receiving portion 21 is specified by the illustrated leftinclination shaded area, while the plan state opening area Sb of theporthole inlet portion 24 e is specified by the illustrated rightinclination shaded area. In this embodiment, it is required to set theratio (2×Sb/Sa) of the plan state opening area (2×Sb) of the portholeinlet portions 24 e to the plan state area Sa of the pressure receivingportion 21 so as to fall within the range of 0.15 to 0.80. It ispreferably set to 0.25 to 0.75, more preferably 0.3 to 0.75. That is,when the area ratio (2×Sb/Sa) is set within the aforementioned range,the billet as a metallic material can be stably introduced from theporthole inlet portions 24 e into the die while keeping sufficient planstate opening area of the porthole inlet portion 24 e, which makes itpossible to obtain an extruded product with high quality.

In other words, if the area ratio (2×Sb/Sa) is too large, the openingarea of the die case 20 becomes large, which may cause deterioration ofstrength of the die case 20. To the contrary, if the area ratio(2×Sb/Sa) is too small, the introduction amount of a billet into theportholes 24 becomes small, resulting in excessive pressure (extrusionload) of the billet against the die, which may cause difficulty insmooth extrusion.

In this embodiment, it is preferable that the billet pressure receivingsurface 22 of the die case 20 is constituted by a convex sphericalsurface of a ⅙ to 4/6 sphere. When the billet pressure receiving surface22 is constituted by the aforementioned specific convex sphericalconfiguration, the pressing force of a metallic billet can be moreassuredly received by the billet pressure receiving surface 22 in awell-balanced dispersed manner, resulting in sufficient strength, whichin turn can more assuredly extend the die life. That is, when a billetis pressed against the pressure receiving surface 22 having the specificconvex spherical configuration, compressing force toward the center ofthe pressure receiving portion 21 is more assuredly applied to eachportion of the pressure receiving surface 22. As a result, the shearingforce to be generated at the die case 20 at the time of the extrusionwill be assuredly reduced. As a result, the portion of the die case 20exposed to the hollow portion thereof, which is the portion where thelargest shearing force will be generated, can be reduced assuredly.Thus, the strength of the die 10 against the pressing force of thebillet can be improved more assuredly. In addition to the above, it alsomakes it possible to simplify the die configuration, reduce the size andweight, and also attain the cost reduction. In other words, if thebillet pressure receiving surface 22 is formed into a configurationconstituted by a convex spherical surface of a sphere smaller than a ⅙sphere, such as, e.g., a convex spherical surface constituted by a ⅛sphere, sufficient strength against the billet pressing force cannot beobtained, which may cause deteriorated die life due to generation ofcracks. To the contrary, if the billet pressure receiving surface 22 isformed into a configuration constituted by a convex spherical surface ofa sphere exceeding a 4/6 sphere, such as, e.g., a convex sphericalsurface configuration of a ⅚ sphere, the cost may be increased due tothe complicated configuration.

In this embodiment, the sphere with a ratio, such as, e.g., a ⅛ sphere,a ⅙ sphere, or a 4/6 sphere, is defined by a partial sphere obtained bycutting a perfect sphere with a plane perpendicular to the axis of theperfect sphere. That is, in this embodiment, an “n/m sphere “m” and “n”are natural numbers, and n<m)” is defined by a partial sphere obtainedby cutting a perfect sphere with a plane perpendicular to the axis ofthe perfect sphere at a position where a distance from a surface of theperfect sphere to an inner position of the perfect sphere on the axis(diameter) is n/m where the length of the axis (diameter) of the perfectsphere is “1.”

As shown in FIG. 5, in this embodiment, the inner side surface 24 a andthe outer side surface 24 b among the inner periphery of the porthole 24are arranged approximately in parallel with each other and alsoapproximately in parallel to the axis A2 of the porthole 24.Furthermore, the inner side surface 24 a and the outer side surface 24 bof the porthole inner periphery are constituted as an inclined surface(tapered surface) inclined to the axis A1 of the die case 20,respectively.

The extrusion die 10 having the aforementioned structure is set in anextruder as shown in FIGS. 9 to 11. That is, the extrusion die 10 ofthis embodiment is set to a container 6 with the extrusion die 10 fixedin the die installation hole 5 a formed in the center of a plate 5. Theextrusion die 10 is fixed by the plate 5 in a direction perpendicular tothe extrusion direction and also fixed by a backer (not illustrated) inthe extrusion direction.

A metallic billet (metallic material), such as, e.g., an aluminumbillet, inserted in the container 6 is pressed in the right direction(extrusion direction) in FIG. 9 via a dummy block 7. Thereby, themetallic billet is pressed against the billet pressure receiving surface22 of the die case 20 constituting the extrusion die 10 to beplastically deformed. As a result, the metallic material passes throughthe pair of portholes 24 and 24 while being plastically deformed andthen reaches the welding chamber 12 of the die case 20. Then, themetallic material is forwardly extruded through the extrusion hole 11into a cross-sectional configuration corresponding to the openingconfiguration of the extrusion hole 11. Thus, a metallic extrudedarticle (hollow member 60) is manufactured.

According to the extrusion die 10 of this embodiment, since the billetpressure receiving surface 22 is formed into a convex sphericalconfiguration, when the metallic billet is pressed against the billetpressure receiving surface 22, the pressing force can be received by thepressure receiving surface 22 in a dispersed manner. Therefore, thepressing force to be applied to each portion of the billet pressurereceiving surface 22 in the direction of a normal line can be reduced,thereby increasing the strength against the pressing force of themetallic material, which results in sufficient durability.

In this embodiment, since the plan state opening area Sb of the portholeinlet portions 24 e with respect to the plan state area Sa of thepressure receiving portion 21 is set to a specific value, it becomespossible to smoothly introduce the billet into the inside of the diefrom the porthole inlet portions 24 e. Thus, the pressing force(extrusion load) of the billet against the pressure receiving surface 22can be decreased appropriately, resulting in efficient and smoothextrusion. Thus, a high quality extruded product can be manufactured.

Furthermore, in this embodiment, the portholes 24 for introducingmaterial are formed in the pressure receiving portion 21 covering themale die 30 and the female die 40. In other words, the front end wallportion of the pressure receiving portion 21 and the wall portion of thebase portion 25 are formed integrally and continuously in the peripheraldirection. The existence of this continued peripheral wall portion canfurther increase the strength of the die case 20, which in turn canfurther increase the strength of the entire extrusion die. Thus, thereis no portion weak in strength, such as a conventional bridge portion,and therefore it is not required to increase the size, such as, e.g.,the thickness, beyond the necessity for the purpose of increasing thestrength, which makes it possible to attain the size and weightreduction as well as the cost reduction.

Furthermore, in this embodiment, the portholes 24 and 24 are formed atpositions away from the axis A1 of the pressure receiving portion 21,i.e., the outer periphery of the pressure receiving portion 21, and theaxis A2 of each porthole 24 is inclined with respect to the axis A1 ofthe die case 20 so as to gradually approach the axis A1 of the die case20 toward the downstream side. Therefore, the metallic material passingthrough the portholes 24 and 24 can be stably extruded while beingsmoothly introduced toward the axis A1, i.e., the extrusion hole 11.Furthermore, in this embodiment, since the downstream side end portions(outlets)) of the portholes 24 and 24 are faced toward the extrusionhole 11, the metallic material can be more smoothly introduced to theextrusion hole 11.

Furthermore, in this embodiment, since the portholes 24 and 24 arearranged at both sides of the height direction (thickness direction) ofthe flat extrusion hole 11, the metallic material can be more smoothlyintroduced into the extrusion hole 11 in a stable manner. Accordingly,the metallic material is extruded while evenly passing through theentire area of the extrusion hole 11 in a well-balanced manner, tothereby obtain a high quality extruded hollow member 60.

Especially like in this embodiment, even in the case of extruding ahollow member 60 having a complicated configuration, such as, e.g., aflat harmonica tube configuration, metallic material can be introducedinto the entire region of the extrusion hole 11 in a well-balancedmanner, which can assuredly maintain the high quality.

For reference, in cases where an aluminum heat exchanging tube (hollowmember) provided with a plurality of passages 63 each rectangular incross-section having a height of 0.5 mm and a width of 0.5 mm, in aconventional extrusion die, since the strength was not sufficient,cracks to be generated in the male die 30 became a factor of the dielife. On the other hand, in the extrusion die 10 according to thepresent invention, since the strength is sufficient, no crack will begenerated in the die. Therefore, wear of the die becomes a factor of thedie life, which can remarkably improve the die life.

For example, according to experiment results relevant to a die lifeperformed by the present inventors, in the extrusion die according tothe present invention, the die life was extended about three times ascompared with a conventional one.

Moreover, in the present invention, since it has sufficient pressureresistance (strength), the extrusion limit speed can be raisedconsiderably. For example, in a conventional extrusion die, the upperlimit of the extrusion speed was 60 m/min. On the other hand, in theextrusion die according to the present invention, the upper limit of theextrusion speed can be raised to 150 m/min, i.e., the extrusion limitspeed can be raised about 2.5 times, and therefore the productiveefficiency can be further improved.

<Modification>

In the first embodiment, the pressure receiving portion 21 (pressurereceiving surface 22) is formed into a hemisphere convex configuration(hemisphere convex surface). However, in the present invention, theconfiguration of the pressure receiving portion 21 (pressure receivingsurface 22) is not limited to the above.

For example, in the present invention, the pressure receiving surface 22can be formed into a polyhedral configuration constituted by a number ofsurfaces. That is, the pressure receiving surface 22 can be formed into,for example, a polyhedral configuration, such as, e.g., a pyramidconfiguration in which a plurality of side surfaces are arranged in thecircumferential direction, or a polyhedral configuration in which aplurality of side surfaces are arranged in the radial direction. In thiscase, each side surface constituting the pressure receiving surface 22can be, for example, a flat surface or a curved surface.

Furthermore, in the present invention, the pressure receiving portion 21can be formed into a laterally elongated configuration longer inlengthwise direction than in crosswise direction, the lengthwisedirection and the crosswise direction being perpendicular to the axialdirection. For example, the pressure receiving portion 21 can be formedinto a laterally elongated elliptical configuration as seen from theaxial upstream side or a laterally elongated oval configuration as seenfrom the axial upstream side.

Furthermore, in the present invention, the pressure receiving portion 21can be formed into a configuration with an axial direction protrudeddimension longer than the radial dimension perpendicular to the axialdirection, e.g., a semi-elliptical configuration.

Furthermore, in the aforementioned embodiment, the die case 20 isintegrally formed. The present invention, however, is not limited to theabove, and the die case can be divided into two or more parts. Forexample, the die case 20 can be constituted by two members, i.e., a maledie case for holding the male die 30 and a female die case for holdingthe female die 40.

Furthermore, in the aforementioned embodiment, the male die 30, thefemale die 40, the flow control plate 50 are formed separately from thedie case 20. The present invention, however, is not limited to theabove, and at least one of the male die 30, the female die 40, and theflow control plate 50 can be formed integrally with the die case 20.Furthermore, in the present invention, the flow control plate 50 can beomitted as needed.

Furthermore, in the aforementioned embodiment, the explanation wasdirected to the die for extruding a flat multi-passage tubular member.In the present invention, however, the configuration of the extrudedproduct (configuration of the extrusion hole) is not specificallylimited. For example, in the present invention, it can be constitutedsuch that a male die is provided with a mandrel round in cross-sectionand a female die is provided with a die hole round in cross-section sothat a circular ring-shaped extrusion hole is defined between themandrel and the die hole to extrude a round tubular member.

In the aforementioned embodiment, the explanation was directed to thecase in which two portholes 24 are formed at both sides of the axis A1.The present invention, however, is not limited to the above, and allowsforming of one porthole 24 or three or more portholes 24.

Furthermore, in the present invention, the configuration of the portholeinlet portion 24 e is not specifically limited. Incases where aplurality of portholes 24 are formed, each porthole inlet portion 24 ecan be different in configuration or different in plan state openingarea of each porthole inlet portion. In summary, it is sufficient thatthe ratio of the total plan state opening area of the porthole inletportions 24 e to the plan state area of the pressure receiving portion21 is set so as to fall within the aforementioned range.

Especially in the case of extruding a tubular member round incross-section, it is preferable to form three or more portholes 24 atequal circumferential intervals.

Furthermore, in the present invention, it can be configured such thatthe opening area of the porthole inlet portion 24 e is formed to belarger than the passage cross-sectional area of the inside of theporthole 24.

That is, in the present invention, for example, like the firstmodification shown in FIG. 14, it can be configured such that theinclination angle θa of the inner side surface 24 a of the portholeinner peripheral surface with respect to the axis A1 of the pressurereceiving portion 21 is set to be smaller than the inclination angle θbof the outer side surface 24 b of the porthole inner peripheral surfacewith respect to the axis A1 of the pressure receiving portion 21 so thatthe thickness (radial direction length) of the porthole inlet portion 24e is larger than the thickness of the inside of the porthole 24.Furthermore, like the second modification shown in FIGS. 15 and 16, whenthe distance between both side edges in the porthole inner peripheralsurface is defined as a “width,” the width of the porthole inlet portion24 e can be formed to be larger than the width of the inside of theporthole 24.

In the present invention, like the third modification shown in FIG. 17,it can be configured such that an outer chamfered portion 242 is formedby cutting the corner portion between the outer side surface 24 b of theporthole inner peripheral surface and the outer side surface of thepressure receiving portion 21 (pressure receiving surface 22) so thatthe opening area of the porthole inlet portion 24 e becomes larger thanthe passage cross-sectional area of the inside of the porthole 24.Alternatively, like the fourth modification shown in FIG. 18, it can beconfigured such that an inner chamfered portion 241 is formed by cuttingthe corner portion between the inner side surface 24 a of the portholeinner peripheral surface and the outer side surface of the pressurereceiving portion 21 (pressure receiving surface 22) so that the openingarea of the porthole inlet portion 24 e becomes larger than the passagecross-sectional area of the inside of the porthole 24. Furthermore, italso can be configured such that both the outer chamfered portion 242and the inner chamfered portion 241 are formed so that the opening areaof the porthole inlet portion 24 e becomes larger than the passagecross-sectional area of the inside of the porthole 24.

Furthermore, in the aforementioned embodiments, the base portion 25 isprovided at the front end portion of the die case 20. In the presentinvention, however, it is not always to provide the base portion 25.

Furthermore, in the aforementioned embodiments, the explanation wasdirected to the case in which only a single extrusion die is set in acontainer. The present invention, however, is not limited to the above.In the extruder according to the present invention, it can be configuredsuch that two or more extrusion dies are set in a container.

In the present invention, it is preferable that the rear end face (basalend face) of the male die 30 is formed as a part of the convex surface(spherical surface) corresponding to the billet pressure receivingsurface 22 of the pressure receiving portion 21 and that the rear endface of the male die 30 and the billet receiving surface 22 constitute aprescribed smooth convex surface (spherical surface). In the presentinvention, however, the configuration of the rear end face (basal endface) of the male die 30 is not limited to the above, and can be, forexample, formed into the following configuration. That is, in thepresent invention, in cases where the surface area of the rear end faceof the male die 30 is, for example, ⅓ or less of the surface area of thebillet pressure receiving surface 22 of the die 10, the rear end face ofthe male die 30 can be constituted by a part of a columnar externalperipheral surface in which the rear end face is circular correspondingto the billet pressure receiving surface 22 in the width direction(longitudinal direction) and straight in the thickness direction(direction perpendicular to the longitudinal direction) because of thefollowing reasons. That is, in cases where the surface area of the rearend face of the male die 30 is small as mentioned above, influence ondie life and extrusion load due to the fact that the rear end face ofthe male die 30 is formed not into a part of a convex surface (sphericalsurface) but into a part of an external periphery of a circular columnis small and the processing cost for the rear end face of the male die30 can be reduced.

EXAMPLE

TABLE 1 Porthole area/Pressure Extrusion receiving Die life Die lifeload portion area (ton/die) limiting factor (×10⁴N) Example 1 0.1  2.0Male die wear, 1,800 Male die minute cracks Example 2 0.15 2.5 Male diewear 1,600 Example 3 0.25 3.0 Male die wear 1,450 Example 4 0.30 3.2Male die wear 1,400 Example 5 0.40 3.5 Male die wear 1,400 Example 60.60 3.7 Male die wear 1,350 Example 7 0.65 3.8 Male die wear 1,300Example 8 0.75 3.8 Male die wear 1,300 Example 9 0.80 2.5 Male die wear,1,250 Case minute cracks Comparative — 0.7 Male die cracks 1,500 Example1

Example 1

As shown in Table 1, an extrusion die 10 corresponding to the firstembodiment was prepared. The pressure receiving portion 21 of the diecase 20 of the die 10 had two portholes 24 formed at both thicknessdirection sides of the extrusion hole 11. The inclination angle θ of theporthole 24 was adjusted to 10°.

The billet pressure receiving surface 22 was formed into a ½ sphericalconfiguration (convex spherical configuration) having a radius of 30 mm.

The ratio (2×Sb/Sa) of the total plan state opening area Sb of theporthole inlet portions 24 e to the plan state area Sa of the pressurereceiving portion 21 was set to 0.1 (the area ratio per porthole was setto 0.05).

The male die 30 was adjusted to 2.0 mm in height (thickness) of mandrel31, 19.2 mm in width of mandrel 31, 1.2 mm in height of passage formingprotruded portion 33, 0.6 mm in width of passage forming protrudedportion 33, and 0.2 mm in width of partition forming groove 32.

The female die 40 was adjusted to 1.7 mm in height of die hole 41 and20.0 mm in width of die hole 41.

As shown in FIGS. 9 to 11, the extrusion die 10 was set to an extrudersimilar to the extruder shown in the first embodiment and extrusion wasperformed to produce a flat multi-passage tubular member 60 (heatexchanging tubular member) as shown in FIGS. 12 and 13.

The die life (the amount (tons) of material introduced until cracks orwear occurs) and the extrusion load were measured, and the die lifelimiting factors were investigated. The results are also shown in Table1.

In Table 1, the “porthole area” denotes the “plan state opening area ofthe porthole inlet portions 24 e,” and the “pressure receiving portionarea” denotes the “plan state area of the pressure receiving portion21.”

Example 2

As shown in Table 1, the ratio (2×Sb/Sa) of the total plan state openingarea Sb of the porthole inlet portions 24 e to the plan state area Sa ofthe pressure receiving portion 21 was set to 0.15 (the area ratio perporthole was set to 0.075).

An extrusion die 10 having the same structure other than the above wasprepared, and extrusion was performed in the same manner as mentionedabove to evaluate in the same manner as mentioned above.

Example 3

As shown in Table 1, the ratio (2×Sb/Sa) of the total plan state openingarea Sb of the porthole inlet portions 24 e to the plan state area Sa ofthe pressure receiving portion 21 was set to 0.25 (the area ratio perporthole was set to 0.125).

An extrusion die 10 having the same structure other than the above wasprepared, and extrusion was performed in the same manner as mentionedabove to evaluate in the same manner as mentioned above.

Example 4

As shown in Table 1, the ratio (2×Sb/Sa) of the total plan state openingarea Sb of the porthole inlet portions 24 e to the plan state area Sa ofthe pressure receiving portion 21 was set to 0.30 (the area ratio perporthole was set to 0.15).

An extrusion die 10 having the same structure other than the above wasprepared, and extrusion was performed in the same manner as mentionedabove to evaluate in the same manner as mentioned above.

Example 5

As shown in Table 1, the ratio (2×Sb/Sa) of the total plan state openingarea Sb of the porthole inlet portions 24 e to the plan state area Sa ofthe pressure receiving portion 21 was set to 0.40 (the area ratio perporthole was set to 0.20).

An extrusion die 10 having the same structure other than the above wasprepared, and extrusion was performed in the same manner as mentionedabove to evaluate in the same manner as mentioned above.

Example 6

As shown in Table 1, the ratio (2×Sb/Sa) of the total plan state openingarea Sb of the porthole inlet portions 24 e to the plan state area Sa ofthe pressure receiving portion 21 was set to 0.60 (the area ratio perporthole was set to 0.30).

An extrusion die 10 having the same structure other than the above wasprepared, and extrusion was performed in the same manner as mentionedabove to evaluate in the same manner as mentioned above.

Example 7

As shown in Table 1, the ratio (2×Sb/Sa) of the total plan state openingarea Sb of the porthole inlet portions 24 e to the plan state area Sa ofthe pressure receiving portion 21 was set to 0.65 (the area ratio perporthole was set to 0.325).

An extrusion die 10 having the same structure other than the above wasprepared, and extrusion was performed in the same manner as mentionedabove to evaluate in the same manner as mentioned above.

Example 8

As shown in Table 1, the ratio (2×Sb/Sa) of the total plan state openingarea Sb of the porthole inlet portions 24 e to the plan state area Sa ofthe pressure receiving portion 21 was set to 0.75 (the area ratio perporthole was set to 0.375).

An extrusion die 10 having the same structure other than the above wasprepared, and extrusion was performed in the same manner as mentionedabove to evaluate in the same manner as mentioned above.

Example 9

As shown in Table 1, the ratio (2×Sb/Sa) of the total plan state openingarea Sb of the porthole inlet portions 24 e to the plan state area Sa ofthe pressure receiving portion 21 was set to 0.80 (the area ratio perporthole was set to 0.40).

An extrusion die 10 having the same structure other than the above wasprepared, and extrusion was performed in the same manner as mentionedabove to evaluate in the same manner as mentioned above.

Comparative Example 1

As shown in Table 1, a bridge-type extrusion die 30 mm in radius andheight (length in the extrusion direction) in 50 mm in which thepressure receiving portion was finished into a flat surfaceperpendicular to the extrusion direction was prepared. The otherstructure was the same as that of the aforementioned examples.

This extrusion die was set to an extruder in the same manner asmentioned above to produce an extruded product, and evaluated in thesame manner as mentioned above.

<Evaluation>

As shown in Table 1, in Comparative Example 1, cracks of the male diewere a life limiting factor, and the die life was short.

On the other hand, in Examples 1 to 9, a longer die life was secured ascompared with Comparative Example 1.

Among other things, in Example 2 to 8 in which the area ratio (2×Sb/Sa)was adjusted to 0.15 to 0.75, the wear of the male die 30 was the lifelimiting factor, and was sufficiently long in die life. The dies ofExamples 3 to 8 in which the area ratio (2×Sb/Sa) was adjusted to 0.25to 0.75, especially the dies of Examples 4 to 8 in which it was adjustedto 0.30 to 0.75, were further longer in die life.

In the dies of Examples 1 and 9, although minute cracks of the male die30 and minute cracks of the die case 20 were life limiting factors, thewear of the male die 30 was the main life limiting factor, which couldsecure certain die life. The life was at least longer than that ofComparative Example 1.

TABLE 2 Spherical size of the billet Die life pressure receiving surface(ton/die) Example 10 ⅛ 1.2 Example 11 ⅙ 2.0 Example 12 ⅓ 2.6 Example 13½ 3.2 Example 14 4/6 3.2 Example 15 ⅚ 3.2

Example 10

As shown in Table 2, an extrusion die 10 corresponding to the firstembodiment (see FIGS. 1 to 8) was prepared. The pressure receivingportion 21 of the die 10 had two portholes 24 formed at both thicknessdirection sides of the extrusion hole 11. The inclination angle θ of theporthole 24 was adjusted to 10°.

The billet pressure receiving surface 22 was constituted by a ⅛ convexspherical surface (convex spherical configuration) having a radius of45.4 mm. The diameter of this pressure receiving portion 21 was adjustedto 60 mm.

The ratio (2×Sb/Sa) of the total plan state opening area Sb of theporthole inlet portions 24 e to the plan state area Sa of the pressurereceiving portion 21 was set to 0.30 (the area ratio per porthole wasset to 0.15).

The male die 30 was adjusted to 2.0 mm in height (thickness) of mandrel31, 19.2 mm in width of mandrel 31, 1.2 mm in height of passage formingprotruded portion 33, 0.6 mm in width of passage forming protrudedportion 33, and 0.2 mm in width of partition forming groove 32.

The female die 40 was adjusted to 1.7 mm in height of die hole 41 and20.0 mm in width of die hole 41.

As shown in FIGS. 9 to 11, the extrusion die 10 was set to an extrudersimilar to the extruder shown in the first embodiment, and extrusion wasperformed to produce a flat multi-passage tubular member 60 (heatexchanging tubular member) as shown in FIGS. 12 and 13.

The die life (ton/die) was measured. The result is shown in Table 2.

Example 11

An extrusion die 10 similar to the extrusion die of Example 10 exceptthat the billet pressure receiving surface 22 was constituted by a ⅙convex spherical surface and the spherical radius was set to 40.3 mm asshown in Table 2 was prepared. The extrusion die 10 was set to anextruder similar to the extruder shown in the first example, andextrusion was performed to produce a flat multi-passage tubular member60 (heat exchanging tubular member).

Example 12

An extrusion die 10 similar to the extrusion die of Example 10 exceptthat the billet pressure receiving surface 22 was constituted by a ⅓convex spherical surface and the spherical radius was set to 32.0 mm asshown in Table 2 was prepared. The extrusion die 10 was set to anextruder similar to the extruder shown in the first example, andextrusion was performed to produce a flat multi-passage tubular member60 (heat exchanging tubular member).

Example 13

An extrusion die 10 similar to the extrusion die of Example 10 exceptthat the billet pressure receiving surface 22 was constituted by a ½convex spherical surface and the spherical radius was set to 30.0 mm asshown in Table 2 was prepared. The extrusion die 10 was set to anextruder similar to the extruder shown in the first example, andextrusion was performed to produce a flat multi-passage tubular member60 (heat exchanging tubular member).

Example 14

An extrusion die 10 similar to the extrusion die of Example 10 exceptthat the billet pressure receiving surface 22 was constituted by a 4/6convex spherical surface and the spherical radius was set to 32.0 mm asshown in Table 2 was prepared. The extrusion die 10 was set to anextruder similar to the extruder shown in the first example, andextrusion was performed to produce a flat multi-passage tubular member60 (heat exchanging tubular member).

Example 15

An extrusion die 10 similar to the extrusion die of Example 10 exceptthat the billet pressure receiving surface 22 was constituted by a ⅚convex spherical surface and the spherical radius was set to 40.3 mm asshown in Table 2 was prepared. The extrusion die 10 was set to anextruder similar to the extruder shown in the first example, andextrusion was performed to produce a flat multi-passage tubular member60 (heat exchanging tubular member).

<Evaluation>

In the die (Example 10) with a large spherical radius of the billetpressure receiving surface 22 and a relatively smaller protruded amountthereof, the die life was slightly shortened.

In the die (Example 15) with a small spherical radius of the billetpressure receiving surface 22 and a relatively larger protruded amountthereof, although long die life can be secured, it is considered to beslightly difficult to process the billet pressure receiving surface 22.

On the other hand, in the dies (Examples 11 to 14) in which the billetpressure receiving surface 22 was formed into an appropriate convexsurface configuration, i.e., a ⅙ to 4/6 spherical convex surface, thedie life could be extended and that the die production cost could bereduced. Among other things, in the die (Example 13) with a ½ sphericalsurface, sufficient die life could be secured and that the dieproduction cost could be reduced, which was excellent in result.

Compared with the die of Example 13, in the die (Example 14) in whichthe billet pressure receiving surface 22 was formed into a 4/6 sphericalsurface, the die production cost was slightly increased, which wasslightly deteriorated in result among Examples 11 to 14.

Second Embodiment

FIGS. 19 to 29 are explanatory views showing an extrusion die formetallic material according to a second embodiment of the presentinvention.

This extrusion die 10 for metallic material according to the secondembodiment is designed to extrude a multi-passage hollow member (flatmulti-passage tube) 60 as shown in FIGS. 28 and 29.

The hollow member 60 is a metal member. In this second embodiment, thishollow member 60 constitutes a heat exchanging tube made of aluminum oraluminum alloy.

This hollow member 60 is a flat member having a width larger than thethickness for use in heat exchangers, such as, e.g., condensers for carair-conditioners. The hollow portion 61 of this hollow member 60 extendsin the tube length direction and is divided into a plurality of heatexchanging passages 63 by a plurality of partitions 62 arranged inparallel with each other. These passages 63 extend in the tube lengthdirection and are arranged in parallel with each other.

In the following explanation of this second embodiment, a direction withwhich a tube length direction perpendicularly intersects and along whichthe passages 63 are arranged will be referred to as a “width direction”or a “lateral direction,” and a direction with which a tube lengthdirection perpendicularly intersects and with which the width directionperpendicularly intersects will be referred to as a “height direction(thickness direction)” or a “vertical direction.” Furthermore, in thefollowing explanation of this second embodiment, the “upstream side”with respect to the extrusion direction will be referred to as a “rearside”, and the “downstream side” thereof will be referred to as a “frontside.”

FIGS. 19 to 24 show an extrusion die 10 of this second embodiment. Asshown in these figures, the extrusion die 10 of this second embodimentis equipped with a die case 20, a male die 30, a female die 40, and aflow control plate 50.

The die case 20 has a hollow structure having a dome-shaped pressurereceiving portion 21 provided at the upstream side (rear side) withrespect to the extrusion direction of a metallic billet as a metallicmaterial and a base portion 25 provided at the downstream side (frontside).

The surface (rear surface) of the pressure receiving portion 21 opposedagainst the extrusion direction of a metallic billet is formed into abillet pressure receiving surface 22 functioning as a metallic materialpressure receiving surface. This billet pressure receiving surface 22 isformed into a convex configuration protruded in a direction opposite tothe extrusion direction (i.e., in the rear direction). Concretely, thispressure receiving surface 22 is formed into a hemispherical convexconfiguration. Thus, the pressure receiving surface 22 is formed so asto protrude rearward.

In the peripheral wall center of the pressure receiving portion 21, amale die holding slit 23 communicated with an internal hollow portion(welding chamber 12) is formed along the axis A1 of the die case 20.This male die holding slit 23 is formed into a flat rectangularcross-sectional configuration corresponding to the cross-sectionalconfiguration of the male die 30. Furthermore, as shown in FIG. 23, atboth side portions of the rear end side of the male die holding slit 23,engaging stepped portions 23 a and 23 a for engaging the male die 30,which will be mentioned later, are formed.

In the peripheral wall of the pressure receiving portion 21, a pair ofportholes 24 and 24 are formed at both sides of the axis A1. The inletportion 24 e of each porthole 24 is formed into an approximatelytrapezoidal configuration as seen from the upstream side of the axialdirection.

As shown in FIG. 22, each porthole 24 is disposed such that the axis A2thereof approaches the axis A1 of the pressure receiving portion 21 asit advances toward the downstream side and intersects with the axis A1of the pressure receiving portion 21 in an inclined state. The detailstructure of, e.g., the inclination angle θ of the axis A2 of theporthole 24 will be explained later.

Furthermore, each porthole 24 is formed such that the passagecross-sectional area gradually decreases from the inlet portion 24 etoward the inner portion, so that the opening area of the inlet portion24 e is larger than the passage cross-sectional area of the innerportion. In the second embodiment, the porthole 24 is formed such thatthe inclination angle θa of the inner side surface 24 a among the innerperipheral surface with respect to the axis A1 is set to be smaller thanthe inclination angle θb of the outer side surface 24 b with respect tothe axis A1 (i.e., θa<θb).

The pair of portholes 24 and 24 are arranged so that the outlet portions(front end portions) thereof face toward the below-mentioned extrusionhole 11.

In this second embodiment, it is constituted such that the axis A1 ofthe die case 20 and the axis of the pressure receiving portion 21coincide with each other.

The base portion 25 is integrally formed to the pressure receivingportion 21, and formed into an annular shape centered on the axis A1.The base portion 25 has a diameter larger than the diameter of thepressure receiving portion 21.

In this invention, the base portion 25 and the pressure receivingportion 21 are not required to be formed integrally, and can be formedseparately. Whether both the members 21 and 25 should be integrallyformed or separately formed can be arbitrarily selected in considerationof the maintenance performance, etc.

In the base portion 25, a cylindrical female die holding hole 26communicated with a welding chamber 12 and corresponding to thecross-sectional shape of the female die 40 is formed. The axis of thisfemale die holding hole 26 is constituted so as to align with the axisA1 of the die case 20.

At the rear end side of the inner peripheral surface of the female dieholding hole 26, as shown in FIG. 22 for example, an engaging steppedportion 26 a for engaging a female die 40, which will be explainedlater, via a flow control plate 50, is formed.

The front principle portion of the male die 30 is constituted as amandrel 31. As shown in FIGS. 20 and 23, the front end portion of themandrel 31 is configured to form the hollow portion 61 of the hollowmember 60 and has a plurality of passage forming protruded portions 33corresponding to passages 63 of the hollow member 60. These pluralpassage forming protruded portions 33 are arranged in the widthdirection of the mandrel 31 at certain intervals. The gap formed betweenthe adjacent passage forming protruded portions 33 and 33 is constitutedas a partition forming groove 32 for forming the partition 62 of thehollow member 60.

At both the width direction side ends of the rear end portion of themale die 30, engaging protruded portions 33 a and 33 a corresponding tothe engaging stepped portions 23 a and 23 a of the male die holding slit23 of the die case 20 are integrally formed so as to protrude sideways.

The male die 30 is inserted into the male die holding slit 23 of the diecase 20 from the side of the billet pressure receiving surface 22 andfixed therein. In this inserted state, the male die 30 is positionedwith the engaging protruded portions 33 a and 33 a of the male die 30engaged with the engaging stepped portions 23 a and 23 a. Thus, themandrel 31 of the male die 30 is held in the mandrel holding slit 23with the mandrel 31 forwardly protruded from the mandrel holding slit 23by a certain length.

The basal end surface (rear end surface) of the male die 30 is formedinto a partial hemispherical convex surface corresponding to the billetpressure receiving surface 22 of the die case 20. The basal end surface(rear end surface) of the male die 30 and the billet pressure receivingsurface 22 cooperatively form a prescribed smooth hemispherical convexsurface.

The female die 40 is formed into a cylindrical shape and provided withkey protrusions 47 and 47 arranged in parallel with the axis A1 at bothsides on the external peripheral surface thereof as shown in FIG. 20.

The female die 40 is provided with a die hole (bearing hole 41)corresponding to the mandrel 31 of the male die 30 and opened at therear end surface side and a relief hole 42 communicated with the diehole 41 and opened at the front end surface side.

The die hole 41 is provided with an inwardly protruded portion along theinner peripheral edge portion so that the outer peripheral portion ofthe hollow member 60 can be defined. The relief hole 42 is formed into atapered shape gradually increasing the thickness (height) toward thefront end side (downstream side) and opened at the downstream side.

The flow control plate 50 is formed into a round shape in externalperiphery corresponding to the cross-sectional shape of the female dieholding hole 26 of the die case 20. Corresponding to the mandrel 31 ofthe male die 30 and the die hole 41 of the female die 40, a centralthrough-hole 51 is formed in the center of the flow control plate 50.

As shown in FIG. 20, the flow control plate 50 has, at its both sides ofthe external peripheral edge portion, key protrusions 57 and 57corresponding to the key protrusions 47 and 47 of the female die 40 areformed.

As shown in FIGS. 21 to 23, the female die 40 is accommodated and fixedin the female die holding hole 26 of the die case 20 via the flowcontrol plate 50. With this state, the external peripheral surface ofone end surface (rear end surface) of the female die 40 is engaged withthe engaging stepped portion 26 a of the female die holding hole 26 viathe external peripheral edge portion of the flow control plate 50, sothat the female die 40 and the flow control plate 50 are positioned inthe axial direction. Furthermore, the key protrusions 47 and 47 of thefemale die 40 and the key protrusions 57 and 57 of the flow controlplate 50 are engaged with the keyways (not illustrated) formed on theinternal peripheral surface of the female die holding hole 26, so thatthe female die 40 and the flow control plate 50 are positioned in theaxial rotational direction.

With this, the mandrel 31 of the male die 30 and the die hole 41 of thefemale die 40 are disposed corresponding to the central through-hole 51of the flow control plate 50. In this state, the mandrel 31 of the maledie 30 is disposed within the die hole 41 of the female die 40 to form aflat circular extrusion hole 11 between the mandrel 31 and the die hole41. Furthermore, a plurality of partition forming grooves 32 of themandrel 31 are arranged in parallel in the width direction in theextrusion hole 11, whereby a cross-sectional shape corresponding to thecross-sectional shape of the hollow member 60 is formed.

In this second embodiment, as shown in FIG. 22, it is preferable thatthe angle difference (θb-θa) between the inclination angle θb of theouter side surface 24 b and the inclination angle θa of the inner sidesurface 24 a is set to 3 to 37°, more preferably 5 to 25°. When theangle difference (θb-θa) is set so as to fall within the above specifiedrange, the opening area of the porthole inlet portion 24 e can be keptsufficiently large, which makes it possible to stably introduce a billetas a metallic material into the inside of the die. As a result, a highquality extruded product can be formed.

In other words, if the angle difference (θb-θa) is too large, thepassage cross-sectional area of the inside portion of the porthole 24becomes extremely small as compared with that of the inlet portion 24 e,causing sudden pressure changes when the billet passes through theporthole 24, which may sometimes make it difficult to stably introducethe billet into the die. To the contrary, if the angle difference(θb-θa) is too small, the opening area of the inlet portion 24 e cannotbe kept large enough, causing excessively large pressure (extrusionload) of the billet against the die, which may sometimes make itdifficult to smoothly perform the extrusion processing. It is notpreferable to keep the opening area of the inlet portion 24 e large withthe aforementioned angle difference (θb-θa) kept small, because theporthole 24 itself becomes large, increasing the void ratio in the dieby the portholes 24, which causes deteriorated die strength.

As will be explained with reference to the third embodiment to the fifthembodiment, in the present invention, it is possible to increase theopening area of the inlet portion 24 e by setting the angle difference(θb-θa) to 0°.

Furthermore, in the second embodiment, it is preferable to set theinclination angle θa of the inner side surface 24 a of the porthole 24to 3 to 30°, more preferably 5 to 25°. The inclination angle θb of theouter side surface 24 b is preferably set to 10 to 40°, more preferably20 to 30°. That is, in cases where the inclination angle θa of the innerside surface 24 a excessively large or the inclination angle θb of theouter side surface 24 b excessively small, a sufficient opening area ofthe inlet portion 24 e cannot be secured, causing excessively largeextrusion load of the billet, which may sometimes make it difficult toperform smooth extrusion processing. In cases where the inclinationangle θa of the inner side surface 24 a is excessively small or theinclination angle θb of the outer side surface 24 b excessively large,the passage cross-sectional area of the porthole 24 may sometimes becomeexcessively small as compared with the inlet portion 24 e of theporthole 24, which may make it difficult to pass the billet in a stablemanner.

As explained above, each of the portholes 24 and 24 is formed such thatthe axis A2 inclines with respect to the axis A1 of the die case 20. Inthis second embodiment, it is preferable that the inclination angle θ ofthe axis A2 of the porthole 24 with respect to the axis A1 of the diecase 20 is set to 3 to 45°, more preferably 10 to 35°, still morepreferably 15 to 30°. When the inclination angle θ is set so as to fallwithin the above specified range, the metallic material flows throughthe portholes 24 and 24 and the welding chamber 12 in a stable manner,and then smoothly passes through around the entire periphery of theextrusion hole 11 in a balanced manner. As a result, a high qualityextruded product excellent in dimensional accuracy can be formed. Inother words, if the inclination angle θ is too small, the metallicmaterial passed through the portholes 24 and 24 and the welding chamber12 cannot be smoothly introduced into the extrusion hole 11, which maysometimes make it difficult to stably obtain a high quality extrudedproduct. To the contrary, if the inclination angle θ is too large, thematerial flowing direction of the porthole 24 inclines largely, whichincreases the metallic material extrusion resistance, and therefore itis not preferable.

In this second embodiment, it is preferable that the billet pressurereceiving surface 22 of the die case 20 is constituted by a convexspherical surface of a ⅙ sphere to a 4/6 sphere. When the billetpressure receiving surface 22 is constituted by the aforementionedspecific convex spherical configuration, the pressing force of ametallic billet can be more assuredly received by the billet pressurereceiving surface 22 in a well-balanced dispersed manner, resulting insufficient strength, which in turn can more assuredly extend the dielife. That is, when a billet is pressed against the pressure receivingsurface 22 having the specific convex spherical configuration,compressing force toward the center of the pressure receiving portion 21is more assuredly applied to each portion of the pressure receivingsurface 21. As a result, the shearing force generated at the die case 20at the time of the extrusion will be assuredly reduced. As a result, theportion of the die case 20 exposed to the hollow portion thereof, whichis the portion where the largest shearing force will be generated, canbe reduced assuredly. Thus, the strength of the die 10 against thepressing force of the billet can be improved more assuredly. In additionto the above, it also makes it possible to simplify the dieconfiguration, reduce the size and weight, and also attain the costreduction. In other words, if the billet pressure receiving surface 22is formed into a configuration constituted by a convex spherical surfaceof a sphere smaller than a ⅙ sphere, such as, e.g., a convex sphericalsurface constituted by a ⅛ sphere, sufficient strength against thebillet pressing force cannot be obtained, which may cause deteriorateddie life due to generation of cracks. To the contrary, if the billetpressure receiving surface 22 is formed into a configuration constitutedby a convex spherical surface of a sphere exceeding a 4/6 sphere, suchas, e.g., a convex spherical surface configuration of a ⅚ sphere, thecost may be increased due to the complicated configuration.

In this embodiment, the sphere with a ratio, such as, e.g., a ⅛ sphere,a ⅙ sphere, or a 4/6 sphere, is defined by a partial sphere obtained bycutting a perfect sphere with a plane perpendicular to the axis of theperfect sphere. That is, in this embodiment, an “n/m sphere (“m” and “n”are natural numbers, and n<m)” is defined by a partial sphere obtainedby cutting a perfect sphere with a plane perpendicular to the axis ofthe perfect sphere at a position where a distance from a surface of theperfect sphere to an inner position of the perfect sphere on the axis(diameter) is n/m where the length of the axis (diameter) of the perfectsphere is “1.”

The extrusion die 10 having the aforementioned structure is set in anextruder as shown in FIGS. 25 to 27. That is, the extrusion die 10 ofthis embodiment is set to a container 6 with the extrusion die 10 fixedin the die installation hole 5 a formed in the center of a plate 5. Theextrusion die 10 is fixed by the plate 5 in a direction perpendicular tothe extrusion direction and also fixed by a backer (not illustrated) inthe extrusion direction.

A metallic billet (metallic material), such as, e.g., an aluminumbillet, inserted in the container 6 is pressed in the right direction(extrusion direction) in FIG. 25 via a dummy block 7. Thereby, themetallic billet is pressed against the billet pressure receiving surface22 of the die case 20 constituting the extrusion die 10 to beplastically deformed. As a result, the metallic material passes throughthe pair of portholes 24 and 24 while being plastically deformed andthen reaches the welding chamber 12 of the die case 20. Then, themetallic material is forwardly extruded through the extrusion hole 11into a cross-sectional configuration corresponding to the openingconfiguration of the extrusion hole 11. Thus, a metallic extrudedarticle (hollow member 60) is manufactured.

According to the extrusion die 10 of this second embodiment, since thebillet pressure receiving surface 22 is formed into a convex sphericalconfiguration, when the metallic billet is pressed against the billetpressure receiving surface 22, the pressing force can be received by thepressure receiving surface 22 in a dispersed manner. Therefore, thepressing force to be applied to each portion of the billet pressurereceiving surface 22 in the direction of a normal line can be reduced,thereby increasing the strength against the pressing force of themetallic material, which results in sufficient durability.

Furthermore, in the second embodiment, since the porthole 24 is formedsuch that the opening area of the inlet portion 24 e is larger than thepassage cross-sectional area of the inside of the porthole 24, it ispossible to smoothly introduce a billet from the inlet portion 24 e,resulting in appropriately reduced pressing force (extrusion load)against the pressure receiving surface 22 of the billet. As a result,the extrusion processing can be smoothly performed efficiently, which inturn can produce a high quality extruded product.

Especially in the second embodiment, since the porthole 24 is formed soas to gradually decrease from the inlet portion 24 e toward the inside,no sudden change in flow resistance of the billet passing through theportholes 24 occurs, which makes it possible to more smoothly pass thebillet through the portholes 24, resulting in more effective extrusionprocessing.

Furthermore, since the passage cross-sectional area of the inside of theporthole 24 is small, the volume (size) of the porthole 24 can be keptrelatively small, resulting in a small void rate of the die case 20 bythe portholes 24, which can sufficiently increase the strength of thedie case 20. This in turn can sufficiently increase the strength of theentire die.

Furthermore, in this second embodiment, the portholes 24 for introducingmaterial are formed in the pressure receiving portion 21 covering themale die 30 and the female die 40. In other words, the front end wallportion of the pressure receiving portion 21 and the wall portion of thebase portion 25 are formed integrally and continuously in the peripheraldirection. The existence of this continued peripheral wall portion canfurther increase the strength of the die case 20, which in turn canfurther increase the strength of the entire extrusion die. Thus, thereis no portion weak in strength, such as a conventional bridge portion,and therefore it is not required to increase the size, such as, e.g.,the thickness, beyond the necessity for the purpose of increasing thestrength, which makes it possible to attain the size and weightreduction as well as the cost reduction.

Furthermore, in this second embodiment, the portholes 24 and 24 areformed at positions away from the axis A1 of the pressure receivingportion 21, i.e., the outer periphery of the pressure receiving portion21, and the axis A2 of each porthole 24 is inclined with respect to theaxis A1 of the die case 20 so as to gradually approach the axis A1 ofthe die case 20 toward the downstream side. Therefore, the metallicmaterial passing through the portholes 24 and 24 can be stably extrudedwhile being smoothly introduced toward the axis A1, i.e., the extrusionhole 11. Furthermore, in this second embodiment, since the downstreamside end portions (outlets) of the portholes 24 and 24 are faced towardthe extrusion hole 11, the metallic material can be more smoothlyintroduced to the extrusion hole 11.

Furthermore, in this second embodiment, since the portholes 24 and 24are arranged at both sides of the height direction (thickness direction)of the flat extrusion hole 11, the metallic material can be moresmoothly introduced into the extrusion hole 11 in a stable manner.Accordingly, the metallic material is extruded while evenly passingthrough the entire area of the extrusion hole 11 in a well-balancedmanner, to thereby obtain a high quality extruded hollow member 60.

Especially like in this second embodiment, even in the case of extrudinga hollow member 60 having a complicated configuration, such as, e.g., aflat harmonica tube configuration, a metallic material can be introducedinto the entire region of the extrusion hole 11 in a well-balancedmanner, which can assuredly maintain the high quality.

For reference, in cases where an aluminum heat exchanging tube (hollowmember) provided with a plurality of passages 63 each rectangular incross-section having a height of 0.5 mm and a width of 0.5 mm, in aconventional extrusion die, since the strength was not sufficient,cracks generated in the male die 30 became a factor of the die life. Onthe other hand, in the extrusion die 10 according to the presentinvention, since the strength is sufficient, no crack will be generatedin the die. Therefore, the wear of the die becomes a factor of the dielife, which can remarkably improve the die life.

For example, according to experiment results relevant to a die lifeperformed by the present inventors, in the extrusion die according tothe present invention, the die life was extended about three times ascompared with a conventional one.

Moreover, in the present invention, since it has sufficient pressureresistance (strength), the extrusion limit speed can be raisedconsiderably. For example, in a conventional extrusion die, the upperlimit of the extrusion speed was 60 m/min. On the other hand, in theextrusion die according to the present invention, the upper limit of theextrusion speed can be raised to 150 m/min, i.e., the extrusion limitspeed can be raised about 2.5 times, and therefore the productiveefficiency can be further improved.

Third Embodiment

FIGS. 30 to 33 show an extrusion die 10 according to a third embodimentof this invention. As shown in these figures, this extrusion die 10according to the third embodiment is different from the extrusion die 10according to the second embodiment in the configuration (structure) ofthe porthole 24.

That is, in the extrusion die 10 according to the third embodiment, atboth peripheral sides of the pressure receiving portion 21, a pair ofportholes 24 and 24 are formed corresponding to thickness both sides ofthe flat extrusion hole 11. Each porthole 24 is formed into anapproximately trapezoidal configuration as seen from the upstream sidein the axial direction. This porthole 24 has an inlet portion 24 eformed into a flat elongated configuration large in peripheral directionsize (width) and small in radial direction size (thickness).

As shown in FIGS. 32 and 33, this porthole 24 is formed into anapproximately fan shape with a width of the inlet portion 24 e largerthan that of the inside thereof. In detail, the width of the porthole 24gradually decreases from the inlet portion 24 e toward the inside, andthe opening area of the inlet portion 24 e is larger than the passagecross-sectional area of the inside of the porthole 24.

In the third embodiment, the inner side surface 24 a of the innerperipheral surface of the porthole 24 and the outer side surface 24 bthereof are arranged approximately in parallel with each other. Theinclination angle θa of the inner side surface 24 a with respect to theaxis A1 and the inclination angle θb of the outer side surface 24 b withrespect to the axis A1 are approximately equal.

As shown in FIG. 33, when the cross angle (width directional openingangle) between both side edges 24 c and 24 c of the inner peripheralsurface of the porthole 24 is defined as “θw,” it is preferable that theopening angle θw is set to 5 to 45°, more preferably 10 to 40°. When theopening angle θw is set within the aforementioned range, the billet as ametallic material can be stably introduced from the inlet portion 24 eof the porthole 24 into the inside thereof while keeping the openingarea of the porthole inlet portion 24 e sufficiently large. As a result,a high quality extruded product can be obtained.

In other words, if the aforementioned opening angle θw is excessivelylarge, the passage cross-sectional area of the porthole 24 becomesextremely small as compared with the passage cross-sectional area of theinlet portion 24 e of the porthole 24, causing sudden pressure changeswhen the billet passes through the porthole 24, which may sometimes makeit difficult to stably introduce the billet into the die. To thecontrary, if the aforementioned opening angle θw is too small, theopening area of the inlet portion 24 e cannot be secured, causingexcessively large pressure (extrusion load) of the billet against thedie, which in turn may sometime make it difficult to smoothly performthe extrusion processing. If the opening area of the inlet portion 24 eis kept large while keeping the aforementioned opening angle θw small,the porthole itself becomes large. This increases the void rate of thedie by the portholes 24, resulting in deteriorated die strength.Therefore, it is not preferable.

In this third embodiment, since the other structure is essentially thesame as that of the second embodiment, the cumulative explanation willbe omitted by allotting the same reference numeral to the same orcorresponding portion.

This extrusion die 10 according to the third embodiment is also set tothe same extruder shown in FIGS. 25 to 27 used in the second embodimentto perform the extrusion.

In this third embodiment too, the same functions and effects as in thesecond embodiment can be attained.

Fourth Embodiment

FIGS. 34 to 38 show an extrusion die 10 according to a fourth embodimentof this invention. As shown in these figures, the extrusion die 10 ofthis fourth embodiment is different from the extrusion dies 10 of thesecond and third embodiments in the configuration (structure) of theporthole 24.

In this extrusion die 10 of the fourth embodiment, at both sides of theperipheral wall of the pressure receiving portion 21, a pair ofportholes 24 and 24 are formed so as to be located at thickness bothsides of the flat extrusion hole 11. The inlet portion 24 e of thisporthole 24 is formed into an approximately trapezoidal configuration asseen from the upstream side of the axial direction, in the same manneras in the second embodiment.

Furthermore, in this porthole 24, an outer chamfered portion 242 isformed by cutting out the corner portion between the outer side surface24 b of the inner peripheral surface and the pressure receiving surface22.

When the inclination angle of the outer chamfered portion 242 withrespect to the axis A1 is defined as “θ2” as shown in FIG. 38, it ispreferable to set the inclination angle θ2 to 25 to 50°, more preferably30 to 45°.

When the ratio of the length L2 of the chamfered portion to the lengthLb of the outer side surface 24 b of the porthole inner peripheralsurface before forming the outer chamfered portion 242 is defined as thechamfered ratio of the outer chamfered portion 242, the chamfered ratio(L2/Lb) is preferably set to 0.2/1 to 0.9/1, more preferably set to0.4/1 to 0.8/1.

That is, when the inclination angle θ2 of the outer chamfered portion242 and the chamfered ratio (L2/Lb) are set so as to fall within theaforementioned ranges, the extrusion load can be suppressed by theincreased opening area of the porthole inlet portion 24 e, and thereforea billet can be stably introduced into the inside of the die from theinlet portion 24 e of the porthole 24.

In this fourth embodiment, in the state before forming the outerchamfered portion 242 on the outer side surface 24 b of the innerperipheral surface of the porthole 24, the inner side surface 24 a ofthe inner peripheral surface of the porthole 24 and the outer sidesurface 24 b thereof are arranged approximately in parallel with eachother, so that the inclination angle θa of the inner side surface 24 awith respect to the axis A1 and the inclination angle θb of the outerside surface 24 b with respect to the axis A1 are approximately thesame.

In this fourth embodiment, the other structure is substantially the sameas that of the second and third embodiments. Also, in this extrusion die10 of the fourth embodiment, the extrusion can be performed in the samemanner as mentioned above, and the same functions and effects can beattained.

Fifth Embodiment

FIGS. 39 to 43 show an extrusion die 10 according to a fifth embodimentof this invention. As shown in these figures, in this extrusion die 10of the fifth embodiment, at both sides of the peripheral wall of thepressure receiving portion 21, a pair of portholes 24 and 24 are formed.Furthermore, in this porthole 24, an inner chamfered portion 241 isformed by cutting out the corner portion between the inner side surface24 a of the inner peripheral surface and the pressure receiving surface22.

When the inclination angle of the inner chamfered portion 241 withrespect to the axis A1 is defined as “θ1” as shown in FIG. 43, it ispreferable to set the inclination angle θ1 to −10 to +10°, morepreferably −3 to +5°.

When the ratio of the length L1 of the chamfered portion to the lengthLa of the inner side surface 24 a of the porthole inner peripheralsurface before forming the inner chamfered portion 241 is defined as thechamfered ratio of the outer chamfered portion 241, the chamfered ratio(L1/La) is preferably set to 0.2/1 to 0.9/1, more preferably set to0.4/1 to 0.8/1.

That is, when the inclination angle θ1 of the inner chamfered portion241 and the chamfered ratio (L1/La) are set so as to fall within theaforementioned ranges, the extrusion load can be suppressed by theincreased opening area of the porthole inlet portion 24 e, and thereforea billet can be stably introduced into the inside of the die from theinlet portion 24 e of the porthole 24.

In this fifth embodiment, in the state before forming the innerchamfered portion 241 on the inner side surface 24 a of the innerperipheral surface of the porthole 24, the inner side surface 24 a ofthe inner peripheral surface of the porthole 24 and the outer sidesurface 24 b thereof are arranged approximately in parallel with eachother, so that the inclination angle θa of the inner side surface 24 awith respect to the axis A1 and the inclination angle θb of the outerside surface 24 b with respect to the axis A1 are approximately thesame.

In this fifth embodiment, the other structure is substantially the sameas that of the second and third embodiments. Also, in this extrusion die10 of the fifth embodiment, the extrusion can be performed in the samemanner as mentioned above, and the same functions and effects can beattained.

<Modification>

In the second to fifth embodiments, the pressure receiving portion 21(pressure receiving surface 22) is formed into a hemisphere convexconfiguration (hemisphere convex surface). However, in the presentinvention, the configuration of the pressure receiving portion 21(pressure receiving surface 22) is not limited to the above.

For example, in the present invention, the pressure receiving surface 22can be formed into a polyhedral configuration constituted by a number ofside surfaces. That is, the pressure receiving surface 22 can be formedinto, for example, a polyhedral configuration, such as, e.g., a pyramidconfiguration in which a plurality of side surfaces are arranged in thecircumferential direction, or a polyhedral configuration in which aplurality of side surfaces are arranged in the radial direction. In thiscase, each side surface constituting the pressure receiving surface 22can be, for example, a flat surface or a curved surface.

Furthermore, in the present invention, the pressure receiving portion 21can be formed into a laterally elongated configuration longer in thelengthwise direction than in the crosswise direction, the lengthwisedirection and the crosswise direction being perpendicular to the axialdirection. For example, the pressure receiving portion 21 can be formedinto a laterally elongated elliptical configuration as seen from theaxial upstream side or a laterally elongated oval configuration as seenfrom the axial upstream side.

Furthermore, in the present invention, the pressure receiving portion 21can be formed into a configuration with an axial directional dimensionlonger than the radial directional dimension perpendicular to the axialdirection, e.g., a semi-elliptical configuration.

Furthermore, in the aforementioned second to fifth embodiments, the diecase 20 is integrally formed. The present invention, however, is notlimited to the above, and the die case 20 can be divided into two ormore parts. For example, the die case 20 can be constituted by twomembers, i.e., a male die case for holding the male die 30 and a femaledie case for holding the female die 40.

Furthermore, in the aforementioned second to fifth embodiments, the maledie 30, the female die 40, the flow control plate 50 are formedseparately from the die case 20. The present invention, however, is notlimited to the above, and at least one of the male die 30, the femaledie 40, and the flow control plate 50 is integrally formed together withthe die case 20. Furthermore, in the present invention, the flow controlplate 50 can be omitted as needed.

Furthermore, in the aforementioned second to fifth embodiments, theexplanation was directed to the die for extruding a flat multi-passagetubular member. In the present invention, however, the configuration ofthe extruded product (configuration of the extrusion hole) is notspecifically limited. For example, in the present invention, it can beconstituted such that a male die is provided with a mandrel round incross-section and a female die is provided with a die hole round incross-section so that a circular ring shaped extrusion hole is formedbetween the mandrel and the die hole to extrude a round tubular member.

In the aforementioned second to fifth embodiments, the explanation wasdirected to the case in which two portholes 24 are formed at both sidesof the axis A1. The present invention, however, is not limited to theabove, and allows forming of one porthole 24 or three or more portholes24.

Especially in cases where a tubular member round in cross-section isformed by extrusion processing, it is preferable to provided three ormore portholes arranged in the peripheral direction at regularintervals.

Furthermore, in the aforementioned second to fifth embodiments, the baseportion 25 is provided at the front end portion of the die case 20. Inthe present invention, however, it is not always required to provide thebase portion 25.

Furthermore, in the aforementioned second to fifth embodiments, theexplanation was directed to the case in which only a single extrusiondie is set in a container. The present invention, however, is notlimited to the above. In the extruder according to the presentinvention, it can be configured such that two or more extrusion dies areset in a container.

Furthermore, in the present invention, it can be configured such thatboth the outer chamfered portion 242 and the inner chamfered portion 241are formed so that the opening area of the porthole inlet portion 24 eis larger than the passage cross-sectional area of the inside of theporthole 24.

Furthermore, in the present invention, like the aforementioned second tofifth embodiments, it is preferable that the rear end face (basal endface) of the male die 30 is formed as a part of the convex surface(spherical surface) corresponding to the billet pressure receivingsurface 22 of the pressure receiving portion 21 and that the rear endface of the male die 30 and the billet receiving surface 22 constitute aprescribed smooth convex surface (spherical surface). In the presentinvention, however, the configuration of the rear end face (basal endface) of the male die 30 is not limited to the above, and can be, forexample, formed into the following configuration. That is, in thepresent invention, in cases where the surface area of the rear end faceof the male die 30 is, for example, ⅓ or less of the surface area of thebillet pressure receiving surface 22 of the die 10, the rear end face ofthe male die 30 can be constituted by a part of a columnar externalperipheral surface in which the rear end face is circular correspondingto the billet pressure receiving surface 22 in the width direction(longitudinal direction) and straight in the thickness direction(direction perpendicular to the longitudinal direction) because of thefollowing reasons. That is, in cases where the surface area of the rearend face of the male die 30 is small as mentioned above, influence ondie life and extrusion load due to the fact that the rear end face ofthe male die 30 is formed not into a part of a convex surface (sphericalsurface) but into a part of an external periphery of a circular columnis small and the processing cost for the rear end face of the male die30 can be reduced.

Example

TABLE 3 Enlarged direction of Extrusion the porthole Die life Die lifeload inlet portion (ton/Die) limiting factor (×10⁴N) Example 16Thickness 4.0 Male die wear 1,330 direction Example 17 Width 3.5 Maledie wear 1,370 direction Example 18 Thickness 4.5 Male die wear 1,300direction (outer side surface is chamfered) Example 19 Thickness 3.8Male die wear 1,350 direction (inner side surface is chamfered)Reference Not enlarged 3.2 Male die wear 1,400 Example Comparative — 0.7Male die cracks are 1,500 Example 2 generated

Example 1

As shown in Table 3, an extrusion die 10 corresponding to the secondembodiment (see FIGS. 19 to 23) was prepared. The pressure receivingportion 21 of the die case 20 of the die 10 had two portholes 24 formedat both thickness direction sides of the extrusion hole 11. In eachporthole 24, the inclination angle θa of the inner side surface 24 a wasadjusted to 10°, and the inclination angle θb of the outer side surface24 b was adjusted to 25°. Accordingly, this porthole inlet portion 24 eis enlarged in the thickness direction. Furthermore, the width dimensionof each porthole 24 is set to be constant from the inlet portion 24 etoward the inside of the die.

Furthermore, the ratio (2×Sb/Sa) of the total plan state opening area Sbof the porthole inlet portions 24 e to the plan state area Sa of thepressure receiving portion 21 was set to 0.70 (the area ration perporthole 24 was 0.35).

The billet pressure receiving surface 22 was formed into a ½ sphericalconfiguration (convex spherical configuration) having a radius of 30 mm.The male die 30 was adjusted to 2.0 mm in height of mandrel 31, 19.2 mmin width of mandrel 31, 1.2 mm in height of passage forming protrudedportion 33, 0.6 mm in width of passage forming protruded portion 33, and0.2 mm in width of partition forming groove 32.

The female die 40 was adjusted to 1.7 mm in height of die hole 41 and20.0 mm in width of die hole 41.

As shown in FIGS. 25 to 27, the extrusion die 10 was set to an extrudersimilar to the extruder shown in the second embodiment and extrusion wasperformed to produce a flat multi-passage tubular member 60 (heatexchanging tubular member) as shown in FIGS. 28 and 29.

Then, the die life (the amount (tons) of material introduced untilcracks or wear occurred) and the extrusion load were measured, and thedie life limiting factors were also investigated. The results are alsoshown in Table 3.

Example 17

As shown in Table 3, an extrusion die 10 corresponding to the thirdembodiment (see FIGS. 30 to 33) was prepared. That is, the porthole 24of the pressure receiving portion 21 was formed such that the widththereof gradually decreased from the inlet portion 24 e toward theinside thereof. The width directional opening angle θw was set to 15°.Accordingly, this porthole inlet portion 24 e was enlarged in the widthdirection. The inner side surface 24 a of the porthole inner peripheralsurface and the outer side surface 24 b thereof were set to 10° ininclination angle θa and θb and arranged in parallel with each other.

Furthermore, the ratio (2×Sb/Sa) of the total plan state opening areasSb of the porthole inlet portions 24 e to the plan state area Sa of thepressure receiving portion 21 was set to 0.60 (the area ration perporthole 24 was 0.30).

An extrusion die 10 same as that of Example 16 other than theaforementioned structure was prepared, and evaluated in the same manneras mentioned above by performing extrusion processing.

Example 18

As shown in Table 3, an extrusion die 10 corresponding to the fourthembodiment (see FIGS. 34 to 38) was prepared. That is, the inner sidesurface 24 a and outer side surface 24 b of the porthole innerperipheral surface of the pressure receiving portion 21 were set to 10°in inclination angles θa and θb, and arranged in parallel with eachother. Furthermore, at the outer side of the inlet portion 24 e of theporthole 24, a chamfered portion 242 was formed. This outer chamferedportion 242 was set to 45° in inclination angle and 5 mm in length, andthe chamfered rate (L2/Lb) of this chamfered portion 242 was 0.23/1.Therefore, the porthole inlet portion 24 e was enlarged in the thicknessdirection.

Furthermore, the width dimension of the porthole 24 was set to beconstant from the inlet portion 24 e toward the inside of the die.

Furthermore, the ratio (2×Sb/Sa) of the total plan state opening area Sbof the porthole inlet portions 24 e to the plan state area Sa of thepressure receiving portion 21 was set to 0.76 (the area ration perporthole 24 was 0.38).

An extrusion die 10 same as that of Example 16 other than theaforementioned structure was prepared, and evaluated in the same manneras mentioned above by performing extrusion processing.

Example 19

As shown in Table 3, an extrusion die 10 corresponding to the fifthembodiment (see FIGS. 39 to 43) was prepared. That is, the inner sidesurface 24 a and outer side surface 24 b of the porthole innerperipheral surface of the pressure receiving portion 21 were set to 10°in inclination angles θa and θb, and arranged in parallel with eachother. Furthermore, at the inner side of the inlet portion 24 e of theporthole 24, a chamfered portion 241 was formed. This inner chamferedportion 241 was set to 0° in inclination angle (parallel to the axis A1)and 10 mm in length L1, and the chamfered rate (L1/La) of this chamferedportion 241 was 0.35/1. Therefore, the porthole inlet portion 24 e wasenlarged in the thickness direction.

Furthermore, the width dimension of the porthole 24 was set to beconstant from the inlet portion 24 e toward the inside of the die.

Furthermore, the ratio (2×Sb/Sa) of the total plan state opening area Sbof the porthole inlet portions 24 e to the plan state area Sa of thepressure receiving portion 21 was set to 0.60 (the area ration perporthole 24 was 0.30).

An extrusion die 10 same as that of Example 16 other than theaforementioned structure was prepared, and evaluated in the same manneras mentioned above by performing extrusion processing.

Reference Example

As shown in Table 3, the pressure receiving portion 21 was formed into asemispherical configuration having a radius of 30 mm and a height (axiallength) 15 mm.

The inner side surface and outer side surface of the porthole innerperipheral surface of the pressure receiving portion 21 were set to 10°in inclination angles θa and θb, and arranged in parallel with eachother, and the width dimension of the porthole 24 was set to be constantfrom the inlet portion 24 e toward the inside of the die. Accordingly,the porthole inlet portion 24 e was not enlarged.

Furthermore, the ratio (2×Sb/Sa) of the total plan state opening area Sbof the porthole inlet portions 24 e to the plan state area Sa of thepressure receiving portion 21 was set to 0.30 (the area ration perporthole 24 was 0.15).

An extrusion die 10 same as that of Example 16 other than theaforementioned structure was prepared, and evaluated in the same manneras mentioned above by performing extrusion processing.

Comparative Example 2

As shown in Table 3, a bridge-type extrusion die having a radius of 30mm and a height (extrusion direction length) of 50 mm in which thepressure receiving surface was finished into a flat surfaceperpendicularly intersecting with the extrusion direction was prepared.The inclination angle of the metallic material introduction directionwas essentially set to 0°. The other structure was the same as theaforementioned embodiments.

This extrusion die 10 was set to an extruder in the same manner asmentioned above to produce an extruded product, and evaluated in thesame manner as mentioned above.

<Evaluation>

As shown in Table 3, in Examples 16 to 19, wear of the male die 30 was alife limiting factor, and they had a sufficiently long die life.Furthermore, in these Examples, the extrusion load was relatively low,and therefore extrusion could perform smoothly.

On the other hand, in Comparative Example 2, generation of cracks in themale die was a life limiting factor. The die life was short and theextrusion load was large.

In Reference Example, wear of the male die was a life limiting factorand the die life was relatively long. However, the extrusion load waslarger than that of Examples 16 to 19.

TABLE 4 Spherical size of billet Die life pressure receiving surface(ton/die) Example 20 ⅛ 1.7 Example 21 ⅙ 3.0 Example 22 ⅓ 3.6 Example 23½ 4.0 Example 24 4/6 4.0 Example 25 ⅚ 3.8

Example 20

As shown in Table 4, an extrusion die 10 corresponding to the secondexample (see FIGS. 19 to 24) was prepared. The pressure receivingportion 21 of the die case 20 of the die 10 had two portholes 24 formedat both thickness direction sides of the extrusion hole 11. In eachporthole 24, the inclination angle θa of the inner side surface 24 a wasadjusted to 10°, and the inclination angle θb of the outer side surface24 b was adjusted to 25°. Furthermore, the width dimension of eachporthole 24 is set to be constant from the inlet portion 24 e toward theinside of the die.

Furthermore, the ratio (2×Sb/Sa) of the plan state opening area Sb ofthe porthole inlet portions 24 e to the plan state area Sa of thepressure receiving portion 21 was set to 0.70 (the area ration perporthole 24 was 0.35).

The billet pressure receiving surface 22 was formed into a ⅛ convexspherical surface (convex spherical configuration) having a radius of45.4 mm. The male die 30 was adjusted to 60 mm in diameter.

The male die 30 adjusted to 2.0 mm in height (thickness) of mandrel 31,19.2 mm in width of mandrel 31, 1.2 mm in height of passage formingprotruded portion 33, 0.6 mm in width of passage forming protrudedportion 33, and 0.2 mm in width of partition forming groove 32, wasused.

The female die 40 adjusted to 1.7 mm in height of die hole 41 and 20.0mm in width of die hole 41 was used.

As shown in FIGS. 25 to 27, the extrusion die 10 was set to an extrudersimilar to the extruder shown in the second embodiment and extrusion wasperformed to produce a flat multi-passage tubular member 60 (heatexchanging tubular member) as shown in FIGS. 28 and 29.

Then, the die life (ton/die) was measured. The result is shown in Table4.

Example 21

As shown in Table 4, an extrusion die 10 similar to the extrusion die ofExample 20 except that the billet pressure receiving surface 22 wasconstituted by a convex spherical surface of a ⅙ sphere and thespherical diameter was set to 40.3 mm was prepared and set to anextruder similar to the extruder as mentioned above. A flatmulti-passage hollow member 60 was produced by performing extrusion inthe same manner as mentioned above.

Example 22

As shown in Table 4, an extrusion die 10 similar to the extrusion die ofExample 20 except that the billet pressure receiving surface 22 wasconstituted by a convex spherical surface of a ⅓ sphere and thespherical diameter was set to 32.0 mm was prepared and set to anextruder similar to the extruder as mentioned above. A flatmulti-passage hollow member 60 was produced by performing extrusion inthe same manner as mentioned above.

Example 23

As shown in Table 4, an extrusion die 10 similar to the extrusion die ofExample 14 except that the billet pressure receiving surface 22 wasconstituted by a convex spherical surface of a ½ sphere and thespherical diameter was set to 30.0 mm was prepared and set to anextruder similar to the extruder as mentioned above. A flatmulti-passage hollow member 60 was produced by performing extrusion inthe same manner as mentioned above.

Example 24

As shown in Table 4, an extrusion die 10 similar to the extrusion die ofExample 20 except that the billet pressure receiving surface 22 wasconstituted by a convex spherical surface of a 4/6 sphere and thespherical diameter was set to 32.0 mm was prepared and set to anextruder similar to the extruder as mentioned above. A flatmulti-passage hollow member 60 was produced by performing extrusion inthe same manner as mentioned above.

Example 25

As shown in Table 4, an extrusion die 10 similar to the extrusion die ofExample 20 except that the billet pressure receiving surface 22 wasconstituted by a convex spherical surface of a ⅚ sphere and thespherical diameter was set to 40.3 mm was prepared and set to anextruder similar to the extruder as mentioned above. A flatmulti-passage hollow member 60 was produced by performing extrusion inthe same manner as mentioned above.

<Evaluations>

As shown in Table 4, in the die in which the spherical radius of thebillet pressure receiving surface 22 was large and the protruded amountwas relatively small (Example 20), the die life was slightly shortened.

In the die in which the spherical radius of the billet pressurereceiving surface 22 was small and the protruded amount was relativelylarge (Example 25), although the die life could be kept long, it seemsto be slightly difficult to perform the processing of the billetpressure receiving surface 22.

On the other hand, in the die in which the billet pressure receivingsurface 22 was formed into an appropriate convex surface configuration,i.e., a convex spherical surface of a ⅙ to 4/6 sphere (Examples 21 to24), the die life could be extended and the die production cost could bereduced. Among other things, in the die in which the billet pressurereceiving surface 22 was formed into a convex spherical surface of a ½sphere (Example 23), the die production cost could be kept low whilekeeping sufficiently long die life, which was an excellent result.

Comparing with the die according to Example 23, in the die in which thebillet pressure receiving surface 22 was formed into a convex sphericalsurface of a 4/6 sphere (Example 24), the die production cost wasincreased, which was an inferior result among Examples 21 to 24.

It should be understood that the terms and expressions used herein areused for explanation and have no intention to be used to construe in alimited manner, do not eliminate any equivalents of features shown andmentioned herein, and allow various modifications falling within theclaimed scope of the present invention.

While the present invention may be embodied in many different forms, anumber of illustrative embodiments are described herein with theunderstanding, that the present disclosure is to be considered asproviding examples of the principles of the invention and such examplesare not intended to limit the invention to preferred embodimentsdescribed herein and/or illustrated herein.

While illustrative embodiments of the invention have been describedherein, the present invention is not limited to the various preferredembodiments described herein, but includes any and all embodimentshaving equivalent elements, modifications, omissions, combinations(e.g., of aspects across various embodiments), adaptations and/oralterations as would be appreciated by those in the art based on thepresent disclosure. The limitations in the claims are to be interpretedbroadly based on the language employed in the claims and not limited toexamples described in the present specification or during theprosecution of the application, which examples are to be construed asnon-exclusive. For example, in the present disclosure, the term“preferably” is non-exclusive and means “preferably, but not limitedto.” In this disclosure and during the prosecution of this application,means-plus-function or step-plus-function limitations will only beemployed where for a specific claim limitation all of the followingconditions are present in that limitation: a) “means for” or “step for”is expressly recited; b) a corresponding function is expressly recited;and c) structure, material or acts that support that structure are notrecited. In this disclosure and during the prosecution of thisapplication, the terminology “present invention” or “invention” may beused as a reference to one or more aspect within the present disclosure.The language present invention or invention should not be improperlyinterpreted as an identification of criticality, should not beimproperly interpreted as applying across all aspects or embodiments(i.e., it should be understood that the present invention has a numberof aspects and embodiments), and should not be improperly interpreted aslimiting the scope of the application or claims. In this disclosure andduring the prosecution of this application, the terminology “embodiment”can be used to describe any aspect, feature, process or step, anycombination thereof, and/or any portion thereof, etc. In some examples,various embodiments may include overlapping features. In this disclosureand during the prosecution of this case, the following abbreviatedterminology may be employed: “e.g.” which means “for example;” and “NB”which means “note well.”

INDUSTRIAL APPLICABILITY

The extrusion die for a metallic material according to the presentinvention can be applied to manufacture an extruded product such as ahollow tube, for example, a heat exchanging tube for use in car airconditioners, evaporators, or household hot-water supply equipments.

1. An extrusion die for a metallic material, comprising: a die casehaving a pressure receiving portion with an outer surface functioning asa metallic material pressure receiving surface, the die case beingdisposed with the metallic material pressure receiving surface facedrearward against an extrusion direction of the metallic material; a maledie disposed in the die case; and a female die disposed in the die caseto define an extrusion hole between the male die and the female die,wherein the pressure receiving surface is formed into a convexconfiguration protruded rearward, and a porthole for introducing themetallic material is provided in an outer periphery of the pressurereceiving portion, wherein a ratio of an opening area of an inletportion of the porthole defined by a plan view as seen from an axialupstream side (a plan state opening area of the inlet portion of theporthole) to an area of the pressure receiving portion defined by a planview as seen from the axial upstream side (a plan state area of thepressure receiving portion) is set to 0.15 to 0.80, and wherein theextrusion die is configured such that the metallic material pressurizedagainst the metallic material pressure receiving surface is introducedin the die case via the porthole and passes through the extrusion hole.2. The extrusion die for a metallic material as recited in claim 1,wherein the porthole is configured such that the opening area of theinlet portion is larger than a passage cross-sectional area of an insideof the porthole.
 3. The extrusion die for a metallic material as recitedin claim 1, wherein the porthole is configured such that a passagecross-sectional area gradually decreases from the inlet portion towardan inside of the porthole.
 4. The extrusion die for a metallic materialas recited in claim 1, wherein the porthole is configured such that aradial length (thickness)) of the inlet portion is set to be larger thana thickness of an inside of the porthole.
 5. The extrusion die for ametallic material as recited in claim 1, wherein the porthole isconfigured such that a circumferential length (width) of the inletportion is set to be larger than a width of an inside of the porthole.6. The extrusion die for a metallic material as recited in claim 1,wherein the metallic material pressure receiving portion is constitutedby a convex spherical surface of a ⅙ to 4/6 sphere.
 7. The extrusion diefor a metallic material as recited in claim 1, wherein a plurality ofportholes are formed at regular intervals in a circumferential directionabout an axis of the die case.
 8. The extrusion die for a metallicmaterial as recited in claim 1, wherein the porthole is arranged towardthe extrusion hole.
 9. The extrusion die for a metallic material asrecited in claim 1, wherein an inclination of an axis of the portholewith respect to an axis of the die case is set to 3 to 45°.
 10. Theextrusion die for a metallic material as recited in claim 1, wherein theextrusion hole is formed into a flat cross-sectional configuration witha width larger than a thickness, and wherein the portholes are formed atpositions corresponding to thickness directional both sides of theextrusion die.
 11. The extrusion die for a metallic material as recitedin claim 1, wherein the male die and the female die define a flatcircular extrusion hole with a height (thickness) smaller than a width,wherein a portion of the male die corresponding to the extrusion hole isformed into a comb-like configuration having a plurality of passageforming protrusions arranged in a width direction, and wherein theextrusion die is configured such that the metallic material passesthrough the extrusion hole to form a multi-passage hollow member with aplurality of passages arranged in a width direction.
 12. The extrusiondie for a metallic material as recited in claim 1, wherein the male dieand the female die define a circular extrusion hole, and the extrusiondie is configured such that the metallic material passes through theextrusion hole to form a tubular member circular in cross-section.
 13. Adie case for an extrusion die, comprising a pressure receiving portionwith an outer surface functioning as a metallic material pressurereceiving surface faced rearward against an extrusion direction of themetallic material, the die case being configured to mount a male die anda female die therein, wherein the pressure receiving surface is formedinto a convex configuration protruded rearward, and a porthole forintroducing the metallic material is provided in an outer periphery ofthe pressure receiving portion, wherein a ratio of an opening area of aninlet portion of the porthole defined by a plan view as seen from anaxial upstream side (a plan state opening area of the inlet portion ofthe porthole) to an area of the pressure receiving portion defined by aplan view as seen from the axial upstream side (a plan state area of thepressure receiving portion) is set to 0.15 to 0.80, and wherein the diecase is configured such that the metallic material pressurized againstthe metallic material pressure receiving surface is introduced into thedie case via the porthole and passes through the extrusion hole.
 14. Thedie case for an extrusion die as recited in claim 13, wherein themetallic material pressure receiving portion is constituted by a convexspherical surface of a ⅙ to 4/6 sphere.
 15. An extrusion method for ametallic material, comprising the steps of: preparing a die case,wherein the die case comprises a pressure receiving portion with anouter surface functioning as a metallic material pressure receivingsurface faced rearward against an extrusion direction of the metallicmaterial, a male die mounted in the die case, and a female die mountedin the die case for defining an extrusion hole between the male die andthe female die, wherein the pressure receiving surface is formed into aconvex configuration protruded rearward, and a porthole for introducingthe metallic material is provided in an outer periphery of the pressurereceiving portion, and wherein a ratio of an opening area of an inletportion of the porthole defined by a plan view as seen from an axialupstream side (a plan state opening area of the inlet portion of theporthole) to an area of the pressure receiving portion defined by a planview as seen from the axial upstream side (a plan state area of thepressure receiving portion) is set to 0.15 to 0.80; and introducing themetallic material pressurized against the metallic material pressurereceiving surface into the die case via the porthole to pass through theextrusion hole.